Put your washed and quartered baby bellas in a bowl. Sprinkle with the spelt flour. Stir gently to evenly distribute the flour.
Whisk the eggs in a second bowl. Combine the bread crumbs, garlic powder, onion powder, paprika, oregano, basil, Parmesan, salt, and black pepper in a third bowl.
Mist your air fryer baking racks with the oil spray.
Dip the mushroom pieces first in the whisked egg and then in the bread crumb mixture. Place the mushrooms on your air fryer racks in a single layer. I used two air fryer trays.
When all of your mushrooms have been coated, mist them with the oil spray. Drizzle the melted butter over the mushrooms if you've chosen to include it.
Air fry the coated mushrooms for 5 minutes at 350°F (175°C). If you skipped the butter, mist the mushrooms. with the oil spray once more. Switch the position of the racks in the oven.
Air fry for an additional 5 minutes at 350°F (175°C). (Your cooking times may vary depending on the air fryer you are using!)