Reserve 1 tablespoon sugar.
Mix remaining sugar; plums, 2 tablespoons flour, and spices; place in 8–inch cake pan.
Combine and mix remaining flour, reserved 1 tablespoon sugar, baking powder and salt.
Add butter and cut into flour mixture until mixture resembles coarse cornmeal.
Add milk to flour mixture and stir until moistened.
Spoon 8 mounds of dough on top of plum mixture.
Sprinkle brown sugar over dough. Bake at 425°F 25 to 30 minutes or until plum mixture bubbles and thickens and topping browns.