Set your air fryer to 185 degrees Celsius (365 degrees Fahrenheit).
Put the oil, salt, pepper, and optional spices in a freezer bag or a bowl.
Add the chicken breast fillets. If you're using a bag, lightly close it and shake it all together well. If you're using a bowl, rub the spices around on the meat.
Let it stand and marinate for 5 minutes. If you have the time, it can easily stand for 20-30 minutes on the counter or overnight in the fridge.
Place the meat in the air fryer.
Cook them for 8 minutes and turn them. Optionally, add a bit more oil on top.
Cook them for an additional 8 minutes.
Remove them and let them rest on a cutting board (uncovered) for 5-10 minutes.
Feel free to season with freshly ground pepper and a bit of flake salt.
Bon appétit.