Preheat oven to 350°. In a large bowl, cream butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Beat in vanilla. Combine flour, baking powder and salt; add to creamed mixture alternately with milk, beating well after each addition.
Pour into two greased and floured 9-in. round baking pans. Bake 25-30 minutes or until a toothpick inserted in the center comes out clean. Cool 10 minutes before removing from pans to wire racks to cool completely.
Spread frosting between layers and over the top and sides of cake.