Preheat your oven to 375°F (190°C).

Clean the mushrooms under cool water and pat dry. Remove the stems carefully and finely chop them.

In a bowl, combine chopped mushroom stems, cream cheese, sausage or bacon, Parmesan, garlic, parsley, salt, and pepper. Mix until combined.

Stuff each mushroom cap generously with the filling. Arrange them on a greased baking sheet.

Place a small pitted olive in the center of each stuffed mushroom.

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

Remove from oven, let cool slightly, and serve on a platter.