Grandpa'S Perfect Pound Cake
["1 lb. very soft butter", "3 c. sugar", "10 egg yolks", "10 egg whites", "5 1/2 c. sifted flour", "6 tsp. baking powder", "3/4 c. milk", "2 tsp. vanilla", "1 tsp. grated lemon rind"]
["Beat butter with sugar for 5 minutes at low speed.", "Add egg yolks; beat 2 minutes at low speed.", "Beat egg whites 2 minutes at high speed with same beater, then beat creamed mixture 5 minutes longer at low speed.", "Sift 5 1/2 cups flour and baking powder together.", "Beat 1/3 of flour into bowl at low speed.", "Beat in milk until smooth.", "Beat in 1/3 of flour until blended.", "Add egg whites; beat until smooth.", "Reserve 1/4 cup flour.", "Add remaining flour to bowl; increase speed to medium and beat for 5 minutes more.", "Add vanilla and grated lemon rind.", "Beat at medium speed for 2 minutes."]
["very soft butter", "sugar", "egg yolks", "egg whites", "flour", "baking powder", "milk", "vanilla", "lemon rind"]