Preheat oven to 350 degrees F. Spray a baking sheet with cooking spray. Clean mushrooms thoroughly under warm water.

Carefully break off stems. Chop stems extremely fine.

Heat oil in a large skillet over medium heat. Add garlic and chopped mushroom stems to the skillet. Fry until soft, 2-3 minutes.

In a separate bowl, add cream cheese, Mozarella cheese, black pepper, onion powder and chili powder. Add chopped garlic and chopped mushroom stems, stirring together until well blended.

Using a little spoon, fill each mushroom cap with a generous amount of stuffing. Arrange the mushroom caps on prepared cookie sheet.

Bake for 20 minutes in the preheated oven. Serve warm.