Preheat oven to 450 degrees F. While oven is preheating, wash mushrooms with cold water well, drain and place in a bowl.
To remove stems, using your hands just pop it off the cap and use in other dishes.
On a large baking sheet, place mushroom caps tightly packed and touching. Sprinkle with salt and pepper.
Top with Parmesan cheese, concentrating on filling up the cavities.
Bake for 15 minutes or until mushrooms are golden on the outside and cheese has melted. Serve hot.
Notes
Store: Refrigerate in an airtight container for up to 5 days.
Make ahead: Do Step 1-4, tightly wrap baking sheet with plastic and refrigerate for up to 2 days. When ready to serve, if using ceramic baking dish make sure to warm it up on the counter for 30 minutes (to avoid shattering) and then bake by following Step 5.
White mushrooms? You can use white mushrooms however baby bella (brown) mushrooms are more flavorful.
Mushrooms size: Pick medium to large mushrooms for easier stuffing with Parmesan cheese.
Parmesan cheese: It is best to buy a hunk of Parmigiano Reggiano and grate yourself. It is fresh, tastes the best and doesn't contain cellulose like shaker one.