3 tablespoons butter or margarine
1 cup finely chopped onion
3/4 cup catsup
1/4 cup water
3 tablespoons Worcestershire sauce
1/4 cup packed light brown sugar
1 tablespoon tomato paste
1 tablespoon white vinegar
1/4 teaspoon dry mustard
1/4 teaspoon hot pepper sauce
3 tablespoons cocoa
3 1/2 pounds chicken wings

In heavy medium saucepan over medium heat, melt butter; add onion. Cook until tender. Stir in catsup, water, Worcestershire sauce, brown sugar, tomato paste, vinegar, mustard, pepper sauce and cocoa. Heat to boiling, stirring occasionally; remove from heat.

Pour one-half of sauce into 13 x 9-inch glass dish. Place chicken, skin side down in sauce; spoon remaining sauce over chicken. Cover; refrigerate 4 hours or overnight.

Preheat oven to 375 degrees F. Place wings on broiler pan; reserve sauce. Bake 40 to 45 minutes or until chicken is tender, turning over wings and brushing with additional sauce. Serve immediately or refrigerate and reheat later. Keep cooked wings refrigerated no longer than 2 days. If transporting, keep cold in cooler. On grill, reheat wings, if desired.