Preheat the oven to 375°F (190°C).

Gently clean the mushrooms and remove stems, setting the caps aside for stuffing.

In a mixing bowl, combine chopped stems, cream cheese, sausage, Parmesan, garlic, parsley, salt, and pepper until smooth.

Stuff each mushroom cap with the filling, mounding it slightly above the edges.

Use cooking spray or olive oil on a baking sheet and arrange the stuffed mushrooms with space between them.

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

Bake for 20-25 minutes until mushrooms are tender and filling is bubbly.

Let cool briefly, then serve warm on a platter.