Preheat oven to 400°F. Lightly spray 6 medium muffin cups with cooking spray; set aside.
Combine tomato sauce, brown sugar and mustard in small bowl; set aside.
Combine all remaining ingredients in large bowl. Add 1/4 cup reserved sauce mixture to meat mixture and mix in. Divide meat mixture evenly and place into prepared muffin cups. Place muffin pan on baking sheet.
Bake 25 minutes or until no longer pink in centers (165°F). Top each mini loaf with 2 tablespoons sauce; bake 5 minutes more or until sauce is set. Serve with remaining sauce.