Place 2 chicken breast halves in large freezer weight resealable plastic bag. Pound chicken with the side of a heavy can, rolling pin or meat mallet until chicken is 1/4-inch thickness. Repeat process in same bag with remaining chicken breast halves, 2 at a time.
Marinate chicken in salad dressing while preparing stuffing mix.
Preheat oven to 350°F. Combine tomatoes with their liquid, basil and dry stuffing mix; stir just until moistened.
Bake 40 min. Sprinkle with 1/2 cup mozzarella cheese. Bake an additional 5 min. or until chicken is cooked through (170°F) and cheese is melted.