Heat oven to 400°F. Spray 10 regular-size muffin cups with CRISCO® Original No-Stick Cooking Spray, or grease with shortening. In 10-inch skillet, cook beef over medium heat 8 to 10 minutes, stirring occasionally, until thoroughly cooked; drain. Stir in barbecue sauce, onion and brown sugar. Cook 1 minute to blend flavors, stirring constantly.