Step 1

Heat oven to 400ºF.

Step 2

Brown ground beef with onions in skillet; drain. Return meat to skillet. Stir in ketchup and mustard.

Step 3

Spoon into 9-inch square baking dish sprayed with cooking spray; top with remaining ingredients.

Step 4

Bake 30 to 35 min. or until casserole is heated through and potato nuggets are golden brown.