Heat oven to 400°F.
Cut 1/2-inch-thick slice off top of bread loaf; set aside. Remove center of loaf, leaving 1/2-inch-thick shell. Reserve removed bread for making croutons or another use.
Spread inside of bread shell with dressing. Fill with layers of remaining ingredients; cover with top of bread. Wrap in foil.
Bake 30 min. or until sandwich is heated through and cheese is melted.
Let stand 10 min. before cutting to serve.