Cheeseburger Casserole

Directions

1. 1
   Preheat oven to 350 degrees F.
2. 2
   Coat an 11x7-inch baking dish and nonstick skillet with cooking spray.
3. 3
   Cook onion in skillet over medium heat, stirring often.
4. 4
   Crumble in beef; cook, stirring, until browned, about 5 minutes.
5. 5
   Add ketchup, 1/2 t salt and 1/4 t pepper; cook until mixture thickens slightly.
6. 6
   Place bottoms of buns in dish.
7. 7
   Top with beef mixture, pickles and cheese.
8. 8
   Bake until cheese is melted, 15 minutes.
9. 9
   If desired, top with sliced tomatoes.
10. 10
    Cover with bun tops.