Preheat the oven to 350° F. Lightly grease a baking sheet with cooking spray. Clean mushrooms with a damp paper towel. Carefully remove the stems from the mushroom caps, setting the caps aside for later. Add the stems to the bowl of a food processor and pulse in brief bursts until them mushroom stems are finely chopped.

Heat the oil in a large skillet over medium heat. Add the chopped mushroom stems and garlic and cook until all the moisture has disappeared, about 5-7 minutes. Lower the heat to medium-low. Stir in the cream cheese, Parmesan cheese and spices. Stir together until the mixture is smooth and creamy; remove from the heat. Using a small spoon, fill each mushroom cap with a generous amount of filling. Arrange the mushroom caps on the prepared baking sheet. Top with bread crumbs, if desired. Bake for 20 minutes or until the mushrooms are hot and liquid starts to form under the caps. Transfer to a serving platter, garnish with fresh herbs if using and serve immediately.