Preheat oven to 350 degrees F. Line a muffin pan with paper or foil liners. Sift together the flour, baking powder, baking soda, cocoa and salt. Set aside. Cream together the butter and sugar until light and fluffy. Add the eggs one at a time, beating well with each addition, then stir in the vanilla. Add the dry ingredients alternating with the milk; beat well. Fill the muffin cups 3/4 full. Bake for 15 to 17 minutes, or until a toothpick inserted into the cake comes out clean. Frost with buttercream frosting, or chantilly cream.