Remove stems from mushrooms and finely chop; set caps aside. In a large skillet, saute the mushrooms, bacon, red pepper, onion, salt and pepper in oil until vegetables are crisp-tender. Add garlic; cook 1 minute longer.
Remove from the heat. Stir in cheeses. Fill each mushroom cap with about 1 tablespoon of filling.
Place on foil-lined baking sheets. Bake at 400° for 16-20 minutes or until mushrooms are tender.