For the Beef Layer:

• 2 lbs ground beef (80/20)
• 1 medium onion, finely diced
• 3 cloves garlic, minced
• 2 tbsp Worcestershire sauce
• 1 tbsp yellow mustard
• 1 tsp salt
• 1/2 tsp black pepper
• 1 tsp garlic powder
• 1 tsp onion powder

For the “Middle Bun” Layer:

• 6 hamburger buns, torn into pieces
• 2 tbsp butter, melted
• 1 tsp sesame seeds
• 1/2 tsp garlic powder

For the Special Sauce:

• 1 cup mayonnaise
• 1/4 cup ketchup
• 2 tbsp sweet pickle relish
• 1 tbsp yellow mustard
• 1 tbsp white vinegar
• 1 tsp sugar
• 1 tsp paprika
• 1/2 tsp garlic powder
• 1/2 tsp onion powder

For the Casserole Assembly:

• 2 cups shredded cheddar cheese
• 1 cup shredded lettuce
• 1/2 cup dill pickles, chopped
• 1/4 cup diced onion
• 8 slices American cheese