Quickly roll the chicken in the butter mixture cooking for only a few minutes on each side, just enough to brown the chicken. Remove chicken to casserole dish, leaving the mushrooms in the pan. Lay a piece of buttered wax paper over the chicken pieces, once all of the chicken pieces have been put into the casserole dish place in hot oven, leaving the wax paper on. After 6 minutes, press top of chicken with your finger. If still soft, return to oven for a moment or two.When the meat is springy to the touch it is done. Remove the chicken to a warm platter.