Remove stems from mushrooms and finely chop.
Put bacon, stems, onion, and garlic in a frying pan and saute in small amount butter or olive oil.
Cook until onion is soft, then drain.
Stir in remaining ingredients.
Stuff mushroom caps with this mixture.
Place a small pat of butter into the bottom of each compartment of a muffin tin. Place a mushroom in each tin.
Place muffin tins in the oven and bake at 375F degrees for 10 minutes.