Lemonade Layer Cake

Thawed lemonade concentrate gives this tart puff pastry a rich flavor. This cake is the perfect solution for summer birthday parties or winter events when you need to awaken your taste buds.
Preheat the oven to 350 degrees.To make the cake, place the first 5 ingredients in a large bowl; beat with a mixer on medium speed until smooth (about 5 minutes). Add the eggs and egg whites one at a time, beating thoroughly after each addition. Lightly pour the flour into dry measuring cups; smooth with a knife. Combine flour, baking powder, salt, and baking soda; whisk well. Add the flour mixture and buttermilk alternately to the sugar mixture, starting and ending with the flour mixture; beat well after each addition.Pour the batter into 2 (9-inch) round cake pans coated with cooking spray; tap the pan sharply once to remove any air bubbles. Bake at 350 ° C for 20 minutes or until a wooden stick inserted in the center comes out clean. Cool in the tins for 10 minutes on a wire rack; remove from the tins. Cool completely on a wire rack.To make the frosting, put 2 tablespoons butter and the following 4 ingredients (2 tablespoons butter and cream cheese each) in a large bowl; beat with a mixer on high speed until fluffy. Add the powdered sugar and beat on low speed until smooth (do not interrupt). Refrigerate for 1 hour.Place 1 cake on a plate; spread with 1/2 cup icing. Top with the remaining cake. Spread the remaining icing on the top and sides of the cake. Keep the cake loosely closed in the refrigerator.