Lemon Blueberry Cake
This lemon blueberry cake is everything summer dreams are made of — bright, fresh, and packed with flavor in every single bite. The layers are wonderfully moist, and the combination of a tangy lemon buttercream with a rich blueberry reduction frosting makes it genuinely hard to stop at one slice. I've made this one more times than I can count, and it never disappoints.
Ingredients
For the Cake:
- ½ cup whole milk room temperature 120ml
- ½ cup sour cream room temperature 120g
- 3 egg whites room temperature
- 3 tablespoons fresh lemon juice
- 1 tablespoon lemon zest
- 1 tablespoon vanilla extract
- 2 cups all-purpose flour 240g
- 1⅔ cups granulated sugar 333g
- 1½ teaspoons baking powder
- ¼ teaspoon kosher salt
- ¾ cup unsalted butter room temperature 170g
- 1⅓ cups fresh blueberries 180g
For the Reduction:
- 1½ cups fresh blueberries 200g
- 1 tablespoon granulated sugar
- 1 tablespoon fresh lemon juice
- 1 tablespoon water
For the Lemon Buttercream:
- 1½ cups unsalted butter room temperature 340g
- ¼ teaspoon kosher salt
- 6 cups confectioners’ sugar 720g
- 3 tablespoons fresh lemon juice
Instructions
For the Cake:
- Preheat your oven to 350°F (175°C). Grease and lightly flour three 6-inch round cake pans. If you have cake strips, wrap them around the pans to help the cakes bake evenly.
- In a medium bowl, whisk together the milk, sour cream, egg whites, lemon juice, lemon zest, and vanilla until smooth. Set the mixture aside.
- In another bowl, sift together the flour, sugar, baking powder, and salt. Remove 1 tablespoon of the flour mixture and toss it with the blueberries to help keep them from sinking while baking.
- In a large mixing bowl, beat the softened butter until creamy. Add the remaining dry ingredients and mix on low speed until the mixture looks like fine crumbs or wet sand.
- Gradually pour the wet ingredients into the butter mixture while mixing on low speed. Mix just until combined, then beat for about 30 seconds until the batter is smooth and fluffy. Gently fold in the flour-coated blueberries with a spatula.
- Divide the batter evenly between the prepared cake pans, smoothing the tops with a spatula.
- Bake for about 30 minutes, or until the tops spring back when lightly touched or a toothpick inserted in the center comes out clean. Let the cakes cool in the pans for 15 minutes before transferring them to a wire rack to cool completely.
For the Reduction:
- Place ½ cup of the blueberries in the freezer while you prepare the sauce.
- In a small saucepan over medium-low heat, combine the remaining 1 cup blueberries, sugar, lemon juice, and water. Cook until the berries begin to burst, then gently mash them and simmer for a few minutes until the mixture has reduced by about half.
- Strain the blueberry mixture through a fine-mesh sieve into a small bowl, pressing to extract as much liquid as possible. Discard the solids, then refrigerate the blueberry reduction until you're ready to use it.
For the Lemon Buttercream:
- Whip the butter: In a stand mixer fitted with the paddle attachment, beat the butter and salt on medium speed for about 3 minutes, until light and fluffy. Reduce the speed to low and gradually add the powdered sugar, scraping down the bowl as needed. Once combined, beat for another minute until smooth and creamy.
- Add the lemon: Mix in the lemon juice, one tablespoon at a time, until the buttercream reaches your preferred consistency and has a bright lemon flavor.
- Make the blueberry frosting: Scoop about 1 cup of the lemon buttercream into a separate bowl. Stir in the blueberry reduction, one tablespoon at a time, until you're happy with the flavor and color.
- Fill the piping bags: Transfer the blueberry buttercream to a piping bag and snip off the tip. Spoon ½ cup of the lemon buttercream into a piping bag fitted with a decorative tip (846), then place the remaining lemon buttercream into a plain piping bag with the tip snipped off.
For the Assembly:
- Place one cake layer on a serving plate. Pipe a thick ring of lemon buttercream around the edge, then fill the center with the blueberry-lemon buttercream. Add the next cake layer and repeat.
- Cover the top and sides of the cake with lemon buttercream, smoothing it with an offset spatula. For a semi-naked finish, use a thinner layer on the sides and gently scrape away the excess.
- Pipe a ring of lemon buttercream dollops around the top edge of the cake, fill the center with frozen blueberries, and chill for 20 minutes before slicing and serving.
Notes
- Prep the blueberries: To keep the blueberries from sinking, lightly toss them with a little lemon juice, then coat them with about a tablespoon of flour. As you divide the batter between the pans, spread the berries out with a spoon so they’re evenly distributed instead of clumping together.
- Bake for even cake layers: For soft, evenly baked layers with light, straight edges, wrap damp cake strips around the outside of your cake pans before baking. They help the cakes bake more evenly from edge to center.
- Measure the flour the right way: For the best texture, measure your flour carefully. A kitchen scale is the most accurate option. If you're using measuring cups, fluff the flour first, spoon it into the cup, and level it off with a knife instead of scooping directly from the bag.
- Decorate and save the extra frosting: If you're making a naked cake, you'll likely have some buttercream left over. Save it for frosting cupcakes or freeze it in an airtight container for another baking day.