For barbecue sauce: Simmer chicken stock and onions over medium heat for 5 minutes. Add catsup, garlic powder, and brown sugar. Simmer 15-20 minutes, stirring frequently. Set aside.

 

Rinse chicken in cold water. Drain well. Arrange 25 pieces of chicken on each sheet pan (18 x 26 x 1"). Brush 3/4 to 1 qt of barbecue sauce over chicken in each pan. Bake uncovered until tender, checking frequently. Cook in conventional oven at 425 degrees F for 45 minutes or 375 degrees in convection oven for 30 minutes. Transfer to steamable pans for serving.