https://www.simplyrecipes.com/recipes/classic_stuffed_mushrooms/
Ingredients
18 to 24 button or cremini mushrooms, scrubbed clean, stems separated from the caps, stems finely chopped
1 tablespoon butter
2 small shallots, minced (about 2 tablespoons)
1 large garlic clove, minced
2 tablespoons chopped walnuts
Salt
2 tablespoons chopped parsley
1 teaspoon herbes de Provence or dried thyme
2 tablespoons breadcrumbs
2 tablespoons sherry
2 tablespoons extra virgin olive oil
2 tablespoons grated Parmesan cheese