In a medium skillet, melt butter over medium heat. Saute onions and garlic until browned. While onions are cooking, wash and remove stems from mushrooms. In a small bowl, stir cheeses, salt and pepper together. Pour cooked onions into cheese mixture and stir. Stuff about 1 tablespoon filling into each mushroom cavity. Wrap 1 slice Butterball Turkey Bacon around each mushroom, securing with a toothpick. Place under hot broiler or onto hot grill and cook until bacon is cooked to your liking, basting with BBQ sauce and turning occasionally. Serve warm.

*I like to grill these mushrooms face down first so the filling gets sealed in by the seared bacon. Some filling might ooze out, but it should be minimal.