I agree that chicken thighs or drumsticks would be tastier and less expensive. If you like, you may pull the skin off the thighs (it is less expensive to buy thighs with skin on and pull it off yourself than buy skinless thighs). Dredge the chicken in seasoned flour and brown. Put a little of your favorite pasta sauce on the bottom of a casserole, add the chicken pieces and more sauce. Cover and bake at about 325 degrees F until chicken is tender and almost falls off the bone. Uncover, add some grated cheese and cook a few more minutes uncovered until cheese is browned ( may have to increase oven temperature a little). Serve over cooked noodles, rice, baked potatoes, or polenta.
When would you add this to the OP's original casserole? This looks like a whole new dinner.