Step 1 – Creaming the Fats and Sugar: In a spacious mixing bowl or the bowl of a stand mixer fitted with the paddle attachment, combine the softened unsalted butter, vegetable oil, granulated sugar, and sea salt. Beat these ingredients together on medium-high speed until the mixture becomes visibly light in color and incredibly fluffy. This creaming process incorporates air, which is essential for a light cake. Remember to pause halfway through and scrape down the sides and bottom of the bowl with a rubber spatula to ensure everything is evenly combined. This typically takes about 1-2 minutes.

Step 2 – Incorporating Wet Ingredients: Add the room-temperature eggs one at a time to the butter mixture, beating thoroughly after each addition until fully incorporated. Scrape down the bowl after adding each egg to ensure a smooth, emulsified batter. Next, stir in the pure vanilla extract, sour cream, fresh lemon juice, and grated lemon zest. Beat well until all these wet ingredients are fully combined and the mixture is uniform. Ensure all ingredients are at room temperature to prevent the batter from curdling.

Step 3 – Adding Dry and Liquid Alternately: Sift half of the all-purpose flour along with all of the baking powder and baking soda directly into the wet ingredients in the bowl. Gently fold with a rubber spatula until the dry ingredients are mostly incorporated. Then, sift in the remaining flour and pour in the buttermilk. Continue to fold carefully, just until no dry streaks of flour are visible. Be careful not to overmix, as this can develop the gluten too much, leading to a dense cake.

Step 4 – Preparing and Folding in Blueberries: In a separate small bowl, gently toss the fresh or frozen blueberries with the reserved tablespoon of all-purpose flour. This step helps prevent the blueberries from sinking to the bottom of the cake layers during baking, ensuring they are evenly distributed. Carefully fold the floured blueberries into the cake batter. Be sure to leave behind any excess dry flour at the bottom of the blueberry bowl – you only want the coated berries in the batter.

Step 5 – Filling the Pans and Baking Prep: Divide the blueberry cake batter evenly among the three prepared baking tins. For precision, use an ice cream scoop or a kitchen scale to ensure each pan receives a similar amount of batter, which promotes even baking. Smooth out the tops of the batter in each pan with an offset spatula. If your oven space is limited, you can place one of the cake layers in the refrigerator while the others bake, then bake it separately.

Step 6 – Baking and Cooling: Bake the cake layers for approximately 20-25 minutes. To check for doneness, insert a toothpick into the center of a cake layer; it should come out mostly clean with only a few moist crumbs attached. Once baked, remove the pans from the oven and let the cake layers cool in their pans for about 5 minutes. This allows them to firm up slightly. After 5 minutes, run a thin knife around the edges of each cake to help release it, then invert them onto a wire cooling rack. Allow the cakes to cool completely before attempting to frost them; warm cakes will melt your frosting.

Step 1: Combining Ingredients and Gentle Heating: In a small saucepan, combine the fresh or frozen blueberries, granulated sugar, fresh lemon juice, cornstarch, and ground cinnamon. Place the saucepan over medium-low heat. Cook the mixture, stirring frequently, until the blueberries begin to release their juices and soften. Continuous stirring is crucial to prevent the filling from sticking to the bottom of the pan and burning. If you notice it getting too dry or starting to stick, you can add a tablespoon or two of water to help it along.

Step 2: Thickening and Cooling: Continue to stir frequently until the mixture simmers gently and visibly thickens to a consistency similar to pie filling. If, after simmering, your filling isn’t as thick as desired, mix together an extra teaspoon of cornstarch with a teaspoon of sugar in a separate small bowl, then gradually stir this into the simmering filling to help it thicken further. Once the desired consistency is reached, remove the saucepan from the heat and transfer the hot blueberry filling to a heat-safe, non-metal container. Allow it to cool completely to room temperature before chilling it in the refrigerator until you’re ready to assemble your cake. Chilling is vital for the filling to firm up properly.

Step 1: Preparing the Base Frosting: First, ensure your unsalted butter is softened but still slightly cool – it should yield to a gentle finger press without leaving a greasy residue. In a large mixing bowl or the bowl of a stand mixer, beat the softened butter on medium-high speed until it becomes wonderfully light and fluffy, incorporating plenty of air. Gradually add the sifted powdered sugar, about half a cup at a time, beating well after each addition. Continue to beat until the mixture is light, airy, and fluffy, scraping down the sides of the bowl frequently to ensure everything is evenly combined. This process takes a few minutes and is crucial for a smooth, lump-free frosting.

Next, add the full-fat brick-style cream cheese, piece by piece, beating well after each addition until it’s fully incorporated and the frosting becomes light and fluffy. Ensure the cream cheese has only softened for about 10 minutes at room temperature; if it’s too warm, the frosting may become runny and difficult to work with.

Step 2: Infusing Blueberry Flavor and Color: Set aside about half of your prepared blueberry filling mixture for later use in the cake layers and for garnish. Take the remaining half (approximately 4-6 tablespoons) and puree it until smooth using a blender or an immersion blender. Alternatively, you can mash it very well with a fork until all the blueberries are thoroughly broken up. Gradually add this blueberry puree to your cream cheese frosting, one tablespoon at a time. Beat thoroughly after each addition until the puree is fully incorporated and the frosting takes on a beautiful purple hue and a fluffy consistency. It’s important not to add too much blueberry puree too quickly, as excess liquid can cause the frosting to split or become too thin and “gloopy.” Add gradually and observe the consistency and color carefully until you reach your desired result.

Finally, using a rubber spatula, gently fold the finished frosting a few times. This helps to remove any large air pockets or bubbles that may have formed during beating, resulting in an even smoother and more professional-looking frosting for your cake.

Step 1: Laying the Foundation: To begin, place a small dollop of blueberry cream cheese frosting in the center of your cake board or desired serving plate. This acts as an anchor to prevent the cake from sliding. Carefully place the first cooled cake layer onto the frosting. Spread a thin, even layer of frosting over the top of this cake layer. Using a piping bag fitted with a star tip (or simply with the end snipped off), pipe a sturdy border of frosting around the edge of the cake layer. This border should be at least 1.5 inches thick and 0.5 inches tall; it will act as a dam to hold the blueberry filling in place.

Step 2: Adding the Filling and Stacking: Gently spoon 2-3 tablespoons of your chilled blueberry filling into the center of the piped frosting border. Carefully spread the filling out, ensuring it touches the frosting border without overflowing. Be mindful not to add too much filling, as this can cause the cake layers to slide or the filling to seep out the sides. Place the next cooled cake layer on top, pressing down gently to secure it. Repeat the thin frosting layer and piping border process, then add another layer of blueberry filling. This layered approach creates distinct, delicious sections.

Step 3: Final Layer and Chill: Carefully place the third, top layer of cake onto the stack. At this point, it’s beneficial to pop the entire blueberry birthday cake into the freezer for about 10 minutes. This quick chill allows the frosting to firm up slightly, making the cake much more stable and easier to handle for the next steps. While the cake chills, keep any unused frosting in the refrigerator. If it becomes too firm after prolonged chilling (more than 15 minutes), you might need to beat it lightly again until it regains its light and fluffy consistency.

Step 4: Crumb Coat and Final Frosting: Once the cake is chilled, remove it from the freezer. Begin by applying a thin “crumb coat” of frosting all over the top and sides of the cake. This thin layer traps any loose crumbs, ensuring a smooth, clean finish for your final frosting layer. Allow the crumb coat to set in the fridge for another 15-20 minutes. Then, apply a generous second layer of your blueberry cream cheese frosting to cover the top and sides of the cake completely. Make sure to reserve some frosting for piping decorative elements on top. Use a long metal spatula or a cake scraper to smooth the sides and top of the cake, achieving a professional and polished look. Take your time with this step for the best results.

Step 5: Decorative Piping: With the remaining reserved frosting, fill your piping bag. Carefully pipe a beautiful decorative border around the very top edge of your blueberry birthday cake. This not only adds an elegant touch but also creates another small “dam” for the final filling layer.

Step 6: Final Touches and Enjoyment: Carefully spoon the remaining blueberry filling into the middle of the piped border on top of the cake. For an extra visual flourish, you can gently push a small amount of filling over the edge in a few spots to create an inviting “drip” effect down the sides. Finally, decorate your stunning cake with crushed Oreo cookies and/or fresh, plump blueberries for added texture and visual appeal. Your homemade blueberry birthday cake is now complete and ready to be sliced and savored!

📝 Expert Cake Baking & Decorating Tips

Achieving a bakery-worthy blueberry cake is within reach with these expert tips:

• Precision with Flour Measurement: As reiterated earlier, weighing your flour is the golden rule for accurate baking. If you don’t own a kitchen scale, remember the proper “spoon and level” technique: gently stir the flour in its bag or container, then lightly spoon it into your measuring cup. Avoid packing it down. Use the flat edge of a knife to scrape off any excess from the top, ensuring an exact measurement without compacting the flour. This prevents a dense, dry cake.
• Mindful Filling Application: When layering your cake, use the blueberry filling sparingly. A thin, even layer is all you need inside the frosting border. Overfilling can lead to the cake layers sliding around or, worse, the delicious filling oozing out from the sides, making a mess. You may find you have some extra filling, which is a fantastic bonus! Serve any leftover filling alongside individual cake slices for an added treat.
• Frosting Coverage – Your Choice: This recipe provides ample blueberry cream cheese frosting to cover the entire three-layer cake generously. While I personally love a “naked” or semi-naked cake look that subtly reveals the layers, feel free to apply a thicker, smoother coating of frosting if you prefer a more classic, fully frosted appearance. Adjusting the amount of frosting is entirely up to your aesthetic preference.
• Serving Temperature for Optimal Flavor: While this cream cheese frosted cake needs to be stored in the refrigerator due to the dairy, it’s truly best served at room temperature. The butter and cream cheese in the frosting will soften slightly, becoming wonderfully creamy, and the cake layers will regain their ultimate moistness and tender crumb. Remove the cake from the fridge 15-20 minutes before serving to allow it to come to temperature.
• For Impeccable Slices: To achieve beautifully clean and sharp cake slices, always cut the cake while it’s still chilled from the refrigerator. For each cut, use a long, sharp knife, dipping it in hot water and wiping it clean between slices. This technique prevents the frosting from sticking to the knife and ensures every slice is picture-perfect, showcasing those lovely blueberry layers.

Why is my blueberry cream cheese frosting grainy?

A grainy texture in your blueberry cream cheese frosting is typically a sign that you’ve added too much blueberry puree, introducing excess liquid that interferes with the smooth emulsion. To remedy this, continue beating the frosting. If it doesn’t smooth out, try adding an additional quarter cup of sifted icing sugar and a teaspoon of cornstarch (mixed with a tiny bit of lemon juice to prevent lumps) to help absorb the excess moisture and bring the frosting back together. Beat until smooth and fluffy.

How can I fix gloopy or runny cream cheese frosting?

Gloopy or runny frosting is usually a result of cream cheese being too warm or over-beaten. The best solution is to pop the entire bowl of frosting into the fridge for 10-15 minutes to allow the butter and cream cheese to firm up. Once chilled, beat it again. If it’s still too soft, gradually add more sifted icing sugar, a quarter cup at a time, beating after each addition until the desired consistency is reached. To balance any extra sweetness from the added sugar, you can also include a few drops of fresh lemon juice – but be careful not to add too much, as excess liquid will make the frosting gloopy again!

Can I skip the homemade blueberry filling?

While the homemade blueberry filling is highly recommended for its intense flavor and perfect texture, you can indeed skip making it from scratch if time is an issue. If you plan on omitting the filling entirely, I would suggest doubling the frosting recipe to ensure you have enough to generously fill and cover all the cake layers. Alternatively, you can substitute the homemade filling with a good quality store-bought canned blueberry pie filling. However, I strongly advise against using blueberry jam, as its looser consistency and much higher sugar content will likely make the cake excessively sweet and potentially compromise its structural integrity.

I don’t like cream cheese. How do I make blueberry buttercream instead?

If cream cheese isn’t to your taste, you can easily convert this to a delicious blueberry buttercream. Simply substitute the 4 oz (½ cup) of cream cheese with an additional 4 oz (½ cup) of softened unsalted butter. Add this extra butter to the mixing bowl right at the very beginning, along with the initial quantity of butter, oil, sugar, and salt. You might also want to beat in about a teaspoon of freshly squeezed lemon juice at the end to help cut through the richness of the all-butter frosting and provide a balancing tang, similar to what the cream cheese would offer.

How can I achieve a smooth finish on my frosting?

Achieving a beautifully smooth frosting finish requires patience and a few key steps. First, take your time during the crumb coating stage – this thin layer traps all loose crumbs, preventing them from mixing into your final frosting layer. Crucially, as soon as you’ve stacked and filled your cake, pop it into the freezer for 10-15 minutes. This quick chill allows the internal structure of the cake to stabilize and the frosting to set, making it much easier to apply the final, smooth layer without the cake shifting or leaning. Once the cake is firm, apply your final frosting layer using a long offset spatula or a cake scraper, taking slow, even passes. This stability also means your cake will hold its shape better and won’t melt as quickly at room temperature.

Why is blueberry filling coming out the sides of my cake?

If your delicious blueberry filling is oozing out the sides, there are usually two main culprits: you’ve added too much filling between the layers, and/or the frosting borders you piped around the edge of the cake weren’t high or thick enough to act as a proper dam. Remember, you only need a relatively thin layer of blueberry filling within the piped border – typically 2-3 tablespoons per layer is sufficient. Ensure your frosting border is at least 1.5 inches thick and 0.5 inches tall to create a robust barrier. Don’t worry if you have leftover filling; it’s a fantastic bonus to serve alongside individual cake slices!

How long can this blueberry cake sit at room temperature?

Because this blueberry birthday cake features a cream cheese frosting, it requires refrigeration due to the dairy content. It can safely sit at room temperature for a maximum of 1-2 hours. Beyond that, it should be stored in the refrigerator to ensure food safety and maintain the frosting’s stability. For the best eating experience, always allow the chilled cake to sit at room temperature for about 15-20 minutes before serving. This allows the cake layers to soften and the cream cheese frosting to become perfectly creamy, enhancing its overall flavor and texture.

This blueberry birthday cake is super soft, fluffy, and moist. It’s filled with blueberry filling and the best blueberry cream cheese frosting ever. The cake tastes like blueberry with a touch of lemon (don’t add lemon zest if you don’t like the taste of lemon). The filling reminds me of blueberry pie! It’s the perfect blueberry cake for any birthday. It has so much blueberry flavour.

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  3 eight inch round baking pans

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