Heat 1 tablespoon butter in a large skillet over medium high heat. Add the sliced onions and saute for 5-7 minutes, until onions are lightly golden and caramelized. Set aside.

Add remaining butter to the pan along with the mushrooms. Saute for 3-5 minutes until the mushrooms are soft and browned. Add the worcestershire sauce to the pan and cook for another minute. Set aside.

Form 4 patties with the ground meat and season with salt and pepper to your liking. Use your knuckle to create an indentation in the center of each burger. Heat a grill pan over medium high heat and cook the patties for 5-6 minutes on each side, until cooked through.*

Place the cheese slices onto the patties and transfer to a plate covered with foil to rest while you prepare the mayo.

Mix together the mayonnaise, dijon mustard and minced garlic in a small bowl until well combined.

Build your burgers! Spread the mayo sauce on each bun, add the burger, sauteed mushrooms, caramelized onions and your favorite toppings.