Preheat your oven to 375°F (190°C).

Clean the mushrooms with a damp paper towel and remove the stems.

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

Stuff each mushroom cap with the creamy filling, ensuring they are well packed.

Press a small pitted olive into the center of the filling on each mushroom cap.

Arrange stuffed mushrooms on a greased baking sheet and bake for 20-25 minutes until golden and bubbling.

Allow to cool slightly before transferring to a platter for serving.