In a frying pan, fry the bacon on both sides until crispy (5 minutes then turning and frying for an additional 5 minutes).
Remove the bacon from the pan and add in the thinly sliced onions and mushrooms. Saute on medium heat for 5 minutes until tender and caramelized, mixing periodically.
While the onions and mushrooms cook, mix together the ground beef with the Montreal steak seasoning. Form 12 small patties.
Remove the onions and mushrooms and set to the side in a bowl. Mix in 3 tablespoons barbecue sauce into the onions and mushrooms.
Grill the beef patties for 5 minutes, turning once at the 2.5 minute mark. Add the slices of cheddar cheese and close grill. Cook one additional minute until melted. Remove the beef patties from the grill.
To assemble the sliders, slice the King's Hawaiian Sweet Jalapeno Rolls in half. Place a beef patty on the bottom bun, followed by 1/3 piece of bacon, a small spoonful of barbecue onions and mushrooms. Place the top of the bun on and squeeze so that everything is stuck together. Repeat until all 12 sliders are made!