Preheat your oven to 375°F (190°C) and lightly grease a baking dish with olive oil.

Clean the mushrooms with a damp cloth and remove the stems; set caps aside.

In a skillet, cook the Italian sausage over medium heat until browned, about 6-8 minutes. Set aside to cool.

Sauté the chopped mushroom stems, diced onion, and minced garlic in olive oil until soft and fragrant, about 5 minutes.

In a large bowl, combine cooked sausage, sautéed mixture, breadcrumbs, Parmesan cheese, parsley, and cream cheese. Season with salt and black pepper.

Stuff each mushroom cap with the sausage mixture, pressing down slightly to pack them.

Place stuffed mushrooms in the baking dish. Sprinkle with extra Parmesan and drizzle with olive oil. Bake for 25-30 minutes until golden brown.

Remove from oven, let them rest for a few minutes, then serve warm.