In a medium bowl, combine the bacon, cream cheese, jalapeno peppers, ½ cup of shredded cheese, and garlic.
Fill each mushroom cap with a generous amount (about 1 tablespoon) of the cream cheese mixture. Arrange the stuffed mushrooms in a 12-inch cast-iron or oven-safe skillet.
Sprinkle the mushroom caps with the remaining shredded cheese.
Bake 20 minutes, or until cheese is golden brown and melted.