Preheat oven to 350 degrees F (175 degrees C). Grease and flour two 9 inch round cake pans.
In a large bowl, sift together the flour, baking powder, baking soda and salt.
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. Beat in the flour mixture alternately with the milk; beat until smooth.
Pour batter into prepared pans. Bake for 30 to 35 minutes in preheated oven, or until a toothpick inserted into center of cake comes out clean.
Let cool in pan for 10 minutes, then turn out onto a wire rack and cool completely.