Lemon-Lime Layer Cake

Ingredients
Cake:
Cooking spray
1 1/2 cups granulated sugar
1/2 cup butter, softened
3/4 cup egg substitute or equivalent egg
1 tablespoon grated lemon rind
1 tablespoon grated lime rind
1 tablespoon fresh lime juice
2 1/4 cups all-purpose flour (about 10 ounces)
1 1/2 teaspoons baking powder
1 teaspoon baking soda
1/2 teaspoon salt
1 1/3 cups buttermilk

Icing:
1 teaspoon grated lemon rind
1 teaspoon grated lime rind
1 teaspoon fresh lime juice
1 (8-ounce) package cream cheese, softened
2 1/2 cups powdered sugar, sifted (about 10 ounces)
Preparation
Preheat oven to 350°.

To prepare the cake, coat 2 (9-inch) round cake pans with cooking spray; line bottoms of pans with wax paper. Coat wax paper with cooking spray.

Place granulated sugar and butter in a large bowl; beat with a mixer at medium speed until well blended (about 5 minutes). Add egg substitute and the next 3 ingredients (through 1 tablespoon juice); beat well. Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking powder, baking soda, and salt, stirring well with a whisk. Add flour mixture and buttermilk alternately to sugar mixture, beginning and ending with flour mixture. Spoon batter into prepared pans; tap pans once on countertop to remove air bubbles.

Bake at 350° for 30 minutes or until a wooden pick inserted in center comes out clean. Cool in pans on a wire rack 10 minutes; remove cakes from pans. Carefully peel off wax paper. Cool completely on wire racks coated with cooking spray.

To prepare icing, place 1 teaspoon lemon rind and next 3 ingredients (through cream cheese) in a medium bowl; beat with a mixer at medium speed until smooth (about 1 minute). Gradually add powdered sugar, beating at low speed just until blended (do not overbeat). Cover and chill for 30 minutes.

Place 1 cake layer on a plate; spread with 1/2 cup icing. Top with remaining cake layer. Spread remaining icing over top and sides of cake. Chill 1 hour. Store cake loosely covered in refrigerator.