1. Clean the Mushrooms: Gently wipe the mushrooms with a damp cloth or paper towel to remove any dirt. Avoid washing them under water as they can absorb moisture and become soggy.

2. Cut the Mushrooms: Halve each mushroom or cut them into quarters if they are particularly large to ensure even cooking.

3. Mix Ingredients: In a mixing bowl, combine the olive oil, minced garlic, dried thyme, salt, and pepper. Stir until well mixed.

4. Combine with Mushrooms: Add the cleaned mushrooms to the bowl. Toss them gently with the mixture to ensure they are evenly coated. If using, sprinkle the Parmesan cheese over the mushrooms and mix again.

5. Preheat the Air Fryer: Set your air fryer to 375°F (190°C) and allow it to heat up for about 3 minutes.

6. Cook the Mushrooms: Transfer the marinated mushrooms to the air fryer basket. Spread them out evenly; do not overcrowd the basket.

7. Shake the Basket: Cook for 10 minutes. Halfway through, carefully remove the basket and give it a good shake to help the mushrooms cook evenly.

8. Check for Doneness: After 10 minutes, check if the mushrooms are tender and golden. If not, cook for an additional 2-3 minutes or until they reach your desired level of doneness.