Fluffy Cake Frosting: (In my world, there really is no other. It is fabulous. And fluffy. Did I mention that?) *Beat 4 1/2 sticks room-temperature butter and 1 1/2 cups powdered sugar until pale and fluffy. Gradually add an additional 5 1/4 cups powdered sugar. Add 1 1/2 tbsp milk and 1 tsp real vanilla extract. Beat until pale and fluffy.