Preheat Oven:
Preheat oven to 375°F (190°C). Line a baking sheet with parchment paper.
Prepare Mushroom Caps:
Clean mushroom caps with a damp cloth and remove stems. Chop the stems finely and set aside.
Cook Sausage Filling:
In a skillet, heat 1 tbsp olive oil over medium heat. Add sausage and cook until browned, breaking it up with a spoon. Add chopped mushroom stems, garlic, salt, pepper, and cook 3–4 minutes until softened. Remove from heat and stir in breadcrumbs, Parmesan, and parsley.
Stuff the Mushrooms:
Spoon sausage mixture into each mushroom cap, pressing slightly to fill. Arrange on prepared baking sheet.
Add Topping (Optional):
Drizzle 1 tbsp olive oil over stuffed mushrooms and sprinkle with mozzarella cheese if desired.
Bake:
Bake for 20–25 minutes, until mushrooms are tender and the tops are golden brown.
Serve:
Allow to cool slightly and serve warm as an appetizer or party snack.