Arrange chicken in a 13- x 9- x 2-inch baking dish coated with cooking spray. Top chicken with ham and cheese.
Coat a nonstick skillet with cooking spray; place over medium-high heat until hot. Add mushrooms; saute 5 minutes or until tender. Combine mushrooms, soup, and sherry (or broth). Spoon mixture over chicken. Top with stuffing mix; coat well with cooking spray.
To Freeze: Freeze in oven-ready, freezer safe container.
To Reheat: Defrost. Bake at 350 degrees for 45 minutes.