Heat oven to 375ºF. Lightly grease or spray with nonstick cooking spray a 7x11-inch or a 8- or 9-inch square baking dish.
In a 10-inch skillet, cook beef over medium heat, stirring occasionally, until brown; drain. Stir in beans, tomato sauce, brown sugar and onion. Pour into baking dish; set aside.
Unroll dough onto flat surface; firmly press perforations to seal. Using small Halloween-shaped cutter, cut 2 or 3 shapes out of dough. Place dough sheet evenly over top (for square baking dish, fold under short sides to fit). Sprinkle cornmeal all over dough, except on cutout area.