Sift flour once, measure, add baking powder and salt, and sift together three times. Cream butter thoroughly, add sugar gradually and cream after each addition. Add flour alternately with milk, a small amount at a time. Beat well after each addition. Add vanilla. Bake in two greased 9-inch layer pans, 25 to 30 minutes in moderate oven (375°F). Spread boiled frosting between layers and on top and side of cake. Sprinkle thickly with coconut while frosting is still soft. Double the recipe for three 10-inch layers.