1. Clean mushrooms and pull out stems, but save for later. Preheat oven to 400 degrees F, and lightly oil a cookie sheet.
2. Place mushrooms on prepared sheet. Use a food processor to chop onion, mushroom stems, and garlic.
3. Take that mixture and brown in an oiled frying pan. When done, remove from heat and cool.
4. Stir in vegan breadcrumbs, parsley, salt, and pepper. Fill mushrooms (not overfilled past the top) with stuffing, spray lightly with vegetable oil.
5. Put in oven for 15 to 20 minutes or until browned lightly on top.