Combine the flour, baking powder and salt. Sift together at least once, preferably two or three times. Set aside until later. Grease three 9 inch round cake pans or a 13x9 inch pan and line the bottom with wax paper, which has been lightly greased. Place the butter in a mixer bowl. Using the paddle beater on medium-low speed, lightly cream the butter. Add the sugar and vanilla ans continue to cream for 30 seconds or until well blended. Crack the eggs into a measuring cup. Beat briefly with a fork to break the yolks and blend. With the mixer still on medium-low, add the beaten eggs, approximately one egg at the time, beating well after each additon. After all the eggs are added, continue to beat for 2 to 4 minutes or until the mixture begins to appear lighter and fluffier. Add the sifted dry ingredients and milk alternately (about 4 additions each of the dry ingredients and milk beginning and ending with the dry ingredients), while beating on the lowest speed possible. Blend only until all of the ingredients are incorporated and the batter is smooth. Yields about 9 cups of cake batter. Fill the prepared cake pans with the batter and tap pans on a flat surface to release any large air bubbles. Bake in a preheated 350 degree oven (about 30 minutes for 9 inch cake pans, or about 45 minutes for 13x9 inch cake pan) until the cake just begins to shrink from the sides of the pans. Let the cake cool in the pans for about 10 minutes. Turn out, leaving on the wax paper, and allow to cool completely on a wire rack. Remove the wax paper before frosting and assembling the cooled cake layers.