Wash the green beans and trim off the ends if needed.
Add the green beans to a large bowl. Drizzle the 3 Tbsp olive oil over top. Add the 2 Tbsp freshly grated parmesan cheese (if using, it's optional). Sprinkle the ½ tsp garlic powder, ½ tsp onion powder, ½ tsp ground black pepper and ¼ tsp salt.
Toss the green beans together with all the seasonings so that they are evenly coated.
Preheat the air fryer at 350°F for 2 minutes.
Add in the green beans. Use a spatula to scrape along the side of the bowl to get all the oil, parmesan and spices as well. Spread the green beans into an even layer.
Cook for 14 minutes, tossing and shaking the basket with green beans half way through the process. The edges will start to turn golden brown and the parmesan cheese will crispen up during the process.
