Lemon Fluff Cake
["2 c. cake flour", "2 1/2 tsp. baking powder", "1/2 tsp. salt", "1/2 c. butter", "1 c. sugar", "2 tsp. grated lemon rind", "3/4 c. milk", "3 egg whites, beaten"]
["Cream butter; add sugar gradually, creaming until light and fluffy.", "Add lemon rind.", "Sift dry ingredients and add alternately with milk.", "Fold in beaten egg whites and blend in well.", "Bake in 2 greased pans at 375\u00b0 for 25 to 30 minutes."]
["cake flour", "baking powder", "salt", "butter", "sugar", "lemon rind", "milk", "egg whites"]