Gourmet Patty Melts

Ingredients (12)

• + 1 pound ground sirloin add to pantry
• + 1 tablespoon Worcestershire sauce add to pantry
• + 2 cloves garlic, minced, or more to taste add to pantry
• ✓ ½ teaspoon salt
• ✓ ½ teaspoon ground black pepper
• ✓ 3 tablespoons unsalted butter
• + 3 tablespoons olive oil add to pantry
• + 2 medium onions, sliced add to pantry
• + cooking spray add to pantry
• + 4 slices Cheddar cheese add to pantry
• + 4 teaspoons Dijon mustard add to pantry
• + 8 slices rye bread, lightly toasted add to pantry