Directions

1. Preheat oven to 400 degrees.
2. Dice onion.
3. On rimmed 11x17 baking sheet, sprinkle onions and sprinkle with Worcestershire sauce.
4. Using gloves or a piece of plastic wrap, spread ground chuck evenly over the top of onions all the way to edges.
5. Sprinkle with salt and pepper.
6. Place in preheated oven and cook for 18 to 20 minutes.
7. While beef is cooking, slice rolls in half horizontally and squeeze mustard on bottom half of rolls (optional).
8. Remove beef from oven and pour off the drippings.
9. Top evenly with cheese and return to oven to melt.
10. Using pizza cutter, slice beef into twenty four squares and place on rolls with a spatula (about 4 at a time)
11. Replace top of rolls.