Preheat grill with direct and indirect zones to 400F. While grill is preheating brown onions in a skillet with mushrooms and butter until onions are opaque.
Separate ground beef into half pound balls. Using a soda can, press into beef, pressing ground beef sides towards the can to form a bowl. Wrap the outside with a strip of bacon and fill 2 with onions and mushrooms and 2 with mac n cheese. Optionally, add an extra slice of cheese in the bowl first before filling
Place burger bowls over indirect heat and close lid. Grill until bacon is browned. Transfer burger bowls to direct heat and top with cheese and continue grilling until cheese is melted. Place on a bun and serve. Enjoy!