Make the seasoning: On a plate, combine all the dried spices, salt, and pepper.
Season and marinate the chicken: Coat both sides evenly with the blackening seasoning. Using the same plate, cover with plastic wrap and marinate in the refrigerator for 30 minutes.
Preheat the air fryer: Spray the air fryer basket with avocado oil spray and preheat the air fryer for 3 minutes at 360 degrees.
Air fry the chicken: Add the chicken breasts, drizzle with olive oil, and cook for 9 minutes; flip and cook for another 9 minutes, or until the chicken is 165°F.
Rest the chicken: Immediately remove the chicken breasts and allow them to rest for 5-10 minutes before slicing.
Notes
Fennel pollen: This is my SECRET INGREDIENT for this blackening spice rub. and what makes this rub special. I love the flavor; it adds a sweet, citrus, and subtle licorice spice to the rub. If you can't find fennel pollen, you can grind ⅛ teaspoon of fennel seeds and add them to the mix. If you're not a fennel fan, you can omit it completely, but I highly recommend you try it. It's so good.