¼ cup finely chopped onion
5 to 6 slices bacon, chopped
One 8-ounce package cream cheese, softened
¼ cup breadcrumbs
Pinch of salt and ground pepper
2 ½ pounds fresh button mushrooms, stems removed
Preheat the oven to 400 degrees F. Line a rimmed baking sheet with aluminum foil.
In a large skillet, cook the onions and bacon over medium heat until crisp. Remove the mixture from the skillet and set aside. In the same skillet, add the cream cheese and stir constantly until the cream cheese is melted. Add the onion and bacon mixture back into the skillet and mix together. Add the breadcrumbs, salt and pepper and mix together.
Spoon the mixture into the mushroom caps and place on the prepared baking sheet. Bake until the mushrooms are tender, 25 to 35 minutes.