Lemon Blueberry Layer Cake

Celebrate all your special occasions with this showstopper white layer cake. My friend Kathy loves lemon curd and blueberries, so I created this cake for her while our blueberries were at their peak. I split the cake layers to create extra opportunities to spread lemon filling and packed fresh berries across the center layer. See "Tips" below for make-ahead directions.
Prep filling: 35 minutes Chill filling: 2 hours to 1 week Prep batter: 45 minutes Bake: 22 to 24 minutes Bake at: 375°F Yield: 16 to 20 servings Pan: two 9-inch round cake pans Prep frosting: 25 minutes Difficulty: advanced

Ingredients

Lemon Filling

  • 2 tablespoons grated lemon zest (2 lemons)
  • 1/4 cup lemon juice (2 lemons)
  • 1 1/3 cups water
  • 1 cup (200 grams) granulated sugar
  • 3 tablespoons cornstarch
  • 1/4 teaspoon salt
  • 4 tablespoons (1/2 stick) unsalted butter
  • 6 unbeaten large egg yolks (reserve whites for cake batter)

Cake Batter

  • 3 1/3 cups (457 grams) cake flour
  • 1 tablespoon baking powder
  • 1/4 teaspoon salt
  • 1 cup (2 sticks) unsalted butter, softened
  • 2 cups (400 grams) granulated sugar
  • 1 teaspoon vanilla extract (use clear extract for whiter cake)
  • 6 large egg whites, room temperature
  • 1 cup milk, room temperature
  • Baker’s Joy non-stick cooking spray

Buttercream Frosting

  • 1 1/2 cups (3 sticks) unsalted butter, cool, but not cold (70°F)
  • 3/4 teaspoon salt
  • 5 tablespoons whipping cream, cold
  • 1 tablespoon lemon juice (1 lemon)
  • 1 tablespoon vanilla extract (use clear extract for whiter frosting)
  • 3 3/4 cups (420 grams) powdered sugar, sifted
  • 1 1/2 cups fresh blueberries (plus additional to garnish)

Directions

Making the Lemon Filling

  • Grate the lemon zest and prepare the lemon juice; add to the top of a double boiler. Add the water, sugar, cornstarch, salt, butter, and egg yolks to the lemon zest and juice.
  • Cook and stir the filling for 10 to 11 minutes until it is very thick and clarified. Do not let boiling water splash against the base of the pan. The cooked filling should appear smooth and glossy. If you see any lumps of egg, strain the filling through a wire mesh sieve into a bowl.
  • Tightly cover the filling and chill until needed, at least 2 hours or up to a week.

Making the Cakes

  • Preheat the oven to 375°F.
  • Combine the cake flour, baking powder, and salt and sift 3 times.
  • In a large bowl, use an electric mixer at low speed to cream the butter until whipped. Gradually add the sugar and continue beating at medium speed until the mixture is light and fluffy, about 5 to 6 minutes. Add the vanilla and beat to combine.
  • In a separate large bowl, beat the egg whites until stiff. Stir the flour mixture and milk alternately into the creamed mixture, beginning and ending with dry ingredients. Fold in the beaten egg whites until no streaks remain.
  • Prepare two 9-inch round cake pans with Baker’s Joy non-stick cooking spray or grease and flour the pans. Divide the batter and spread evenly in the pans. Bake the cakes at 375°F for 22 to 24 minutes. The cakes are done when they are light mottled brown on top and spring back from a touch. A toothpick inserted in the center will come out clean.
  • Let the cakes cool for 10 minutes in the pans on a wire rack. Run a knife around the edge to loosen the cakes and then turn out on a wire rack to cool completely.

Making the Buttercream Frosting

  • Use an electric mixer at medium-high speed to whip the butter until it is creamy and white in color, about 3 to 4 minutes. Add the salt, cream, lemon juice, and vanilla and beat for about 2 minutes more until the mixture is light and fluffy.
  • Reduce the speed to low and add the powdered sugar a little at a time. Once the sugar is incorporated into the butter, increase the speed to medium-high and beat for 3 to 4 minutes until you have a fluffy, soft, spreadable frosting.

Assembling the Cake

  • Level the cake tops and split the layers.
  • Place the first layer on a cake board with crumb side down. Pipe a border of buttercream frosting to create a “dam” around the outer edge of the layer. Spread 1/2 to 2/3 cup of the lemon filling to taste inside the “dam.”
  • Repeat the process with the second layer and arrange blueberries tightly across the layer.
  • The third layer should be filled in the same manner as the first layer (no blueberries).
  • Spread buttercream frosting across the top and sides. Decorate the top with additional blueberries, if desired.
  • Cover and refrigerate the cake until ready to serve.

Tips

  • The preparation will be less labor intensive if you make the lemon filling 2 days ahead and the buttercream frosting 1 day ahead; cover and chill until needed. Spread the lemon filling chilled and allow the buttercream frosting to warm just until it can be stirred to a smooth consistency.
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