Preheat the oven to 375°F (190°C).

Carefully clean the mushrooms, removing stems while keeping caps intact.

Combine chopped mushroom stems, cream cheese, cooked sausage, grated Parmesan, minced garlic, chopped parsley, salt, and pepper in a mixing bowl and mix well.

Fill each mushroom cap with the prepared filling.

Spray or brush a baking sheet with cooking spray or olive oil and place the stuffed mushrooms on it.

Press a small olive into the center of each stuffed mushroom.

Bake for 20-25 minutes until the mushrooms are tender and tops are bubbly.

Let cool slightly, arrange on a platter and serve warm.