Lemonade Cake

I know, I know, I've been making a lot of fruit desserts lately. But, how could I resist Lemonade Cake! It looks rather plain so next time I'll probably candy some lemon rinds and sprinkle them across the top. I didn't have a chance this time around, unfortunately.
Ingredients:
* 1 1/3 cups granulated sugar
* 6 tablespoons (3/4 stick/3 oz/85g) butter, softened
* 1 tablespoon grated lemon rind
* 3 tablespoons thawed lemonade concentrate
* 2 teaspoons vanilla extract
* 2 large eggs
* 2 large egg whites
* 2 cups all-purpose flour
* 1 teaspoon baking powder
* 1/2 teaspoon salt
* 1/2 teaspoon baking soda
* 1 1/4 cups buttermilk
* Cooking spray
Frosting:
* 2 tablespoons butter, softened
* 2 teaspoons grated lemon rind
* 2 teaspoons thawed lemonade concentrate
* 1/2 teaspoon vanilla extract
* 8 ounces cream cheese
* 3 1/2 cups confectioners' sugar
Directions:
Preheat oven to 350°F (180 C). Place first 5 ingredients in a large bowl; beat with a mixer at medium speed until well blended (about 5 minutes). Add eggs and egg whites, 1 at a time, beating well after each addition. Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking powder, salt, and baking soda; stir well with a whisk. Add flour mixture and buttermilk alternately to sugar mixture, beginning and ending with flour mixture; beat well after each addition.
Pour batter into 2 (9-inch) round cake pans coated with cooking spray; sharply tap pans once on counter to remove air bubbles. Bake in preheated 350°F (180 C) oven for 20 minutes or until wooden pick inserted in center comes out clean. Cool in pans 10 minutes on a wire rack; remove from pans. Cool completely on wire rack.
Place 2 tablespoons butter and the next 4 ingredients (2 tablespoons butter through cream cheese) in a large bowl; beat with a mixer at high speed until fluffy. Add confectioners' sugar, and beat at low speed just until blended (do not overbeat). Chill 1 hour.
Place 1 cake layer on a plate; spread with 1/2 cup frosting. Top with remaining cake layer. Spread remaining frosting over top and sides of cake. Store cake loosely covered in the refrigerator.