Combine stuffing and 1/2 can onions. Spoon stuffing mixture into a 9 inch shallow baking dish. Press stuffing across bottom and up sides of dish to form a shell.
Combine undiluted soup, milk, turkey, and peas; pour into stuffing shell.
Bake, covered, at 350 degrees F (175 degrees C) for 30 minutes. Top with remaining onions. Bake, uncovered, 5 minutes longer. Serve hot.