Bacon Cheeseburger Casserole

1 lb. ground beef

1   onion, chopped

1/3 cup ketchup

2 Tbsp.  yellow mustard

1 cup KRAFT Shredded Sharp Cheddar Cheese

8 slices  OSCAR MAYER Bacon, cooked, crumbled

4 cups (1/2 of 32-oz. pkg.) frozen bite-size seasoned potato nuggets

HEAT oven to 400ºF.
BROWN meat with onions in skillet; drain. Stir in ketchup and mustard; spoon into 9-inch square baking dish sprayed with cooking spray.
TOP with remaining ingredients.
BAKE 30 to 35 min. or until casserole is heated through and potato nuggets are golden brown.