This cake is so delicious. I liked the balance between the light and spongy cake with the rich buttercream. It helped not overload you with richness but still give you a satisfying piece of cake. The buttercream is an amazing recipe. It doesn't have any confectioners' sugar so it doesn't have that sometimes over-the-top sugary taste and instead tastes like pure butter. It was sooo good. I would make it my go-to recipe if my brother wasn't allergic to eggs (although I still might make it my go-to recipe, shhhh!). It does take more time than most cakes but it is a very impressive and delicious result and in my opinion a lot more fun than a plain old yellow birthday cake!
Lemon Sponge Cake
- 5 eggs
- ¾ cup sugar
- ¾ tsp. lemon extract
- 1 cup all-purpose flour, sifted
- 4 Tbsp. butter, melted and cooled
- grated zest of 1 lemon
- 6 Tbsp. fresh lemon juice (I needed 3 lemons)
- 3 Tbsp. orange juice
- 2 large eggs
- ⅓ cup sugar
- 2 Tbsp. butter
- 2 Tbsp. heavy cream
- 1 cup lemon curd (should be all or almost all of the above recipe)
- ½ cup heavy cream
- 1½ cups (3 sticks) butter, softened
- ½ cup milk
- ¾ cup sugar
- 5 egg yolks
- 1 Tbsp. lemon extract
Make the cakes: Preheat oven to 375 degrees F. Line two 9” round cake pans with parchment paper and spray the parchment with nonstick cooking spray.
In the bowl of an electric mixer fitted with the whisk attachment, beat the eggs and sugar on high speed until tripled in volume, about 5 minutes. Beat in the lemon extract. Remove the bowl from the mixer. Sift the flour over the egg mixture in 2 additions and carefully fold in with a large rubber spatula. Fold the melted butter into the mixture, making sure to get all the butter and flour that’s fallen to the bottom of the bowl. Pour into the prepared pans and smooth the top. Bake until the cakes are puffed, 15 to 20 minutes. Let cool completely before filling and frosting.
Make the lemon curd: In a medium pot, combine all the ingredients and cook over medium heat until thickened and registers 175 degrees F on a candy thermometer (I did not measure, I just cooked for exactly 5 minutes on medium heat, which should work fine). Pour into a bowl and refrigerate until needed.
Make the filling: In the bowl of an electric mixer fitted with the whisk attachment, beat the heavy cream until peaks form. Fold into the lemon curd in two additions and set aside.
Make the buttercream: In the bowl of an electric mixer fitted with the flat beater, beat the butter on medium speed until it is the consistency of mayonnaise; it should not be melted. Transfer the butter to another bowl. Thoroughly wash and dry the mixer bowl. In a saucepan over medium heat, combine the milk and ¼ cup of the sugar and heat, stirring occasionally, until small bubbles appear along the edge of the pan.
Meanwhile, in the bowl of the electric mixer fitted with the whisk attachment, beat the egg yolks and the remaining ½ cup sugar on medium-high speed until the mixture is pale and thick, about 3 minutes. Reduce the speed to low and pour in the hot milk mixture in a thin stream. Return the mixture to the saucepan. Thoroughly wash and dry the mixer bowl and the whisk.
Cook the mixture over medium heat, whisking constantly, until it registers 170°F on an instant-read thermometer, 5 to 7 minutes (I just cooked for 6 minutes). Pour the mixture back into the mixer bowl and beat with the whisk on medium speed until cool, 5 to 10 minutes. Beat in the lemon extract. Add the butter in 4 additions, incorporating each addition before adding another.
Assemble the cake: Place one cake, bottom side up, on a cake platter. Using a pastry bag with a large round decorating tip and about ¾ cup of the buttercream, pipe a ring of the buttercream around the outside of the first layer, then pipe another identical ring on top of the first (just to make it thicker). This will act as a stabilizer for the lemon curd filling. Spoon the lemon curd filling on top of the cake and spread to the ring of buttercream. Place the second cake layer on top, with the topside facing the filling (bottom side up again). Frost the cake with a thin crumb coat, then use the remaining frosting to completely frost the cake. If desired, leave about ½ cup buttercream left over for decorating.