Ingredients: – 1 1/2 cups all-purpose flour – 1 1/2 cups cake flour – 2 teaspoons baking powder – 1/4 teaspoon baking soda – 1/2 teaspoon salt – 1 cup unsalted butter, softened – 1 1/2 cups granulated sugar – 2 tablespoons lemon zest (from about 4 medium lemons) – 2 large egg – 4 large egg white – 1 teaspoon vanilla extract – 1/2 cup buttermilk
Instructions: 1. Preheat oven to 350 degrees F. Line the bottom of two 9-inch round baking pans with a piece of parchment paper and lightly spray all over the inside of the pans with nonstick cooking spray.
Sift all-purpose flour and cake flour into a mixing bowl. Add baking powder, baking soda, and salt then stir to combine.
In a separate mixing bowl, add the butter, sugar, and lemon zest then mix with an electric mixer until pale and fluffy, about 3-4 minutes.
Add the whole eggs and mix well. Add the egg whites one at a time, mixing after each. Stir in the vanilla.
Alternately add in a little bit of the flour mixture and then the buttermilk, stirring between each addition. Divide batter evenly between the two prepared round cake pans.
Bake in preheated oven until a toothpick inserted into the center of the cakes comes out clean, about 24-29 minutes.
Remove from oven and allow to cool several minutes in the pans, then transfer to a wire rack to cool completely.