Chop the mushroom stems, dice the onions and celery. In a large skillet over medium heat add the olive oil. When hot add the chopped mushroom stems, onions, celery. Season with salt, pepper and red pepper flakes. Sauté for about 4 minutes until the vegetables just start to soften.
Add the garlic & saute until it becomes fragrant about 30 seconds, remove from heat. Allow to cool.
Combine pork, bread crumbs and cheeses. Add the sauteed vegetables, bread crumbs and egg. Mix by hand until just combined.
Stuff mushrooms and set in an oven proof dish or baking sheet. Sprinkle the top of the mushrooms with a good pinch of the Parmesan cheese. Bake in the oven uncovered for 30 minutes.
Remove from the oven. Set temperature to broil and insert under the broiler. Broil until the tops turns golden brown - about 4-5 minutes depending upon your oven.
Optional - garnish with fresh parsley. Serve and enjoy!
Video
Notes
Variations -
Make gluten-free by using gluten free bread crumbs.
Enjoy vegetarian stuffed mushrooms by omitting the sausage. Substitute with chick peas or add some quinoa - delicious!
For a kick of heat, use hot Italian sausage instead of mild and consider adding a pinch of cayenne pepper.