Lemon-Lime Sunshine Cake

Lemon-Lime Sunshine Cake 1 cup cake flour, sifted three times 1 1/4 cups sugar, sifted five times 4 large egg yolks 8 large egg whites 1/2 tsp salt 1/2 tsp lemon extract Zest of 1/2 fresh lemon Zest of 1/2 fresh lime Preheat oven to 350 degrees Beat egg yolks at highest speed for 4 minutes until yolks are light yellow. Wash beaters. Whip egg whites until frothy; add salt and continue beating until whites volume-ize, holding their shape, but are still moist. Fold sugar, in three passes, into the egg whites, using a rubber spatula to incorporate in an over/under motion. Fold in extract, citrus rind and whipped egg yolks. Fold in flour, again using a rubber spatula to incorporate in an over/under motion. Transfer batter to an ungreased 10-inch tube pan, leveling the surface of the batter with spatula. Bake 40 to 45 minutes until lightly browned (use the toothpick-in- the-center test to make sure cake is done) Invert cake in tube pan to cool. While cake cools, Lemon-Lime Frosting make frosting: Whip sugar with butter and citrus zest, adding citrus juice as you go, to the consistency you desire. Frost cooled cake.