I have a recipe I am making and it calls for cubed cooked chicken to go into the casserole. Once everything is in the baking dish, you cook it in the oven for 30 mins at 350. Last time I put pre-cooked chicken in a casserole, the chicken was overcooked and rubbery. Would you put the chicken in raw and let it cook with the casserole? Partially cook it and let it finish in the casserole? I just don't want it to be tough and chewy. Advice?