Beat granulated sugar and margarine at medium speed of a mixer until well-blended (about 5 minutes). Add molasses and egg; beat well.
Lightly spoon flour into dry measuring cups, and level with a knife. Combine flour and next 5 ingredients (flour through cloves). Add flour mixture to sugar mixture alternately with milk, beginning and ending with flour mixture.
Pour batter into an 8-inch square baking pan coated with cooking spray. Bake at 350° for 30 minutes or until a wooden pick inserted in center comes out clean. Cool in pan on a wire rack. Sift powdered sugar over top of cake, and serve warm.