Step 1

Preheat oven to 350 degrees F (175 degrees C). Prepare a baking sheet with cooking spray.

Step 2

Clean mushrooms with a damp paper towel. Carefully break stems from mushrooms. Chop stems extremely fine.

Step 3

Heat oil in a large skillet over medium heat. Fry chopped mushroom stems and garlic in hot oil until any moisture has disappeared, taking care not to burn the garlic, 3 to 5 minutes. Spread mushroom mixture into a bowl to cool completely, about 10 minutes.

Step 4

Stir cream cheese, Parmesan cheese, black pepper, onion powder, and cayenne pepper with the mushroom stems and garlic until very thick and completely mixed. Use a small spoon fill each mushroom cap with a generous amount of stuffing. Arrange stuffed mushrooms onto the prepared cookie sheet.

Step 5

Bake in preheated oven until piping hot and liquid starts to form under the caps, about 20 minutes.