Preheat oven to 375 degrees. Brown meat with onions in skillet, stirring occasionally; drain. Spoon into 8-inch square baking dish.
Mix soup and milk; pour over meat mixture. Top with layers of mixed vegetables, cheese and potatoes.
Bake for 45 minutes or until potatoes are golden brown and casserole is heated through.
Healthy Living Tip: Save 50 calories and 7 grams of fat per serving by preparing with lean ground beef, reduced fat condensed cream of mushroom soup and Kraft 2% Milk Shredded Reduced Fat Cheddar Cheese.