Lysdahl's Cheesey Hamburgers

Ingredients

• 1 can (10-1/2) oz cream of celery soup
• 1 tablespoon Dijon mustard
• 1/3 to 1/2 cup chili sauce
• 1 teaspoon Worcestershire sauce
• 2 cups grated sharp cheddar cheese
• 1 1/2 pounds ground beef (I use ground sirloin)
• Six onion slices about 1/4 inch thick
• salt & pepper to taste
• 6 hamburger buns, split