Preheat the air fryer to 400°F while you are preparing mushrooms.

Slice mushrooms by placing a wooden spoon at the base of the mushroom cap with the mushroom cap pushed against the spoon, slice through it will stop you so it will create a fan effect.

Repeat this process for every mushroom.

Once all mushrooms are 'fanned' spritz with olive oil atop.

Then dash with garlic salt to taste.

Place in air fryer cavity one by one, and then set to 15 minutes.

While the mushrooms air fry, prepare your caramelized onions.*

Simply place the sliced onions in a frying pan with a tablespoon of olive oil and salt and pepper to taste.

Add a few tablespoons of water as well.

Cover and cook on medium heat, but not HIGH or they will burn.

Fry to caramelize but don't burn.

Remove from heat when done.

Set aside. (they may take longer to cook than the mushrooms and that is fine!

If they are not done at the end of 15 minutes add 5-minute intervals until you achieve a cooked mushroom as photo'd.

Once the mushrooms are done, remove them one by one to a serving platter.

Coat while warm with Pecorino Romano or other grating cheese that you prefer.

Add caramelized onions atop.

Serve.

Refrigerate any leftovers.