Preheat oven to 350 degrees F (175 degrees C). Grease and flour 2 - 9 inch round cake pans.
In a large bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla. Sift together the flour, baking powder, and salt. Beat in the flour mixture alternately with the milk, mixing just until incorporated. Pour batter into prepared pans.
Bake in preheated oven for 40to 45 minutes, or until a toothpick inserted into the center of the cake comes out clean. Let cool in pan for 10 minutes, then turn out onto a wire rack and cool completely.