Preheat oven to 350ºF (180ºC). Butter two 9-inch (23 cm) round baking pans. Line bottom of each pan with parchment or waxed paper. Butter paper. In large bowl, combine flour, cocoa, baking powder, salt, baking soda and sugar. Blend well. Add the butter, milk and vanilla and beat with an electric mixer until well combined. Beating, add eggs one at a time, scraping down the sides of the bowl as needed. Beat for 2 minutes. Divide the batter between pans and bake for about 30 minutes or until tops are springy and cakes begin to pull away from the sides of the pans. Cool on a rack. Decorate as desired.
Makes 10 servings. Baking time: 30 minutes.