Beat the sugar and the butter at medium speed of a mixer until well-blended
(about 5 minutes). Add egg, beating well. Lightly spoon flour into dry measuring
cups; level with a knife.
Combine flour and the next 5 ingredients (flour through salt), stirring
well with a whisk.
Combine milk and vanilla extract. Add the flour mixture to the sugar mixture
alternately with the milk mixture, beginning and ending with the flour mixture.
Pour batter into a 9-inch round cake pan coated with baking spray.
Bake at 350 degrees F for 35 minutes or until a wooden pick inserted in
center comes out clean.
Cool in pan 10 minutes on a wire rack, remove from pan. Cool cake completely
on wire rack.
Place chips in a small heavy-duty zip-top plastic bag, and seal. Submerge
bag in very hot water until chips melt, or microwave on HIGH for 1 minute or
until melted. Snip a tiny hole in one corner of bag; drizzle chocolate over