Because mushrooms like to eat themselves. What a delicious way to describe stuffed mushrooms, right?
Remove stems off button mushrooms and put the stems in a blender with a handful of parmesan cheese and some breadcrumbs, along with garlic, parsley, salt, pepper, and any other seasonings you want. Blend. Stuff the mixture back into the mushrooms, and top with cheese. Brush each mushroom with a little olive oil. Bake for 15 minutes while you vigorously practice your evil laugh.