See blog post for photos on how to stuff the burgers. This is referred to as the "bowl method." Use about 1/4 lb of ground beef and make a bowl shape in your hand.
Add a handful of Muenster and cheddar cheese (as much as you can fit) and fold the burger up over the cheese.
Pinch the burger top closed and press the burger carefully into the shape of a patty.
Sprinkle both side of the burger with Montreal steak seasoning.
Drizzle Worcestershire sauce straight from the bottle over top of all of the burgers. Be generous here and let the burgers soak in this for a few hours.
Grill burgers over medium high heat until done.