Butter a 10 inch cake pan
In a large bowl , stir the sugar, flour, cocoa powder, baking powder, and baking soda and salt until combined.
Add egg, oil, milk, and vanilla beating with mixer on medium speed for 2 minutes. Turn mixer to low beat in water . Batter will be thin.
Pour batter into the prepared pan and bake at 350 or until tooth pick inserted in center comes out clean with a few moist crumbs.
Let cake cool in pan for 10 minutes unmold onto a wire rack and cool completely. Dust with powdered sugar and cut into wedges.
serve with vanilla ice cream and hot fudge sauce
makes 8 servings