Remove turkey breast from its packaging, leaving the netting on to help keep it together while cooking (for boneless). Place it in a large bowl and pat dry well with paper towels. Let it sit on the counter for about 30 minutes before cooking.
If using a bone-in turkey with ribs attached, it’s best to spatchcock the breast. Place the turkey breast side down and use a sharp chef’s knife to score the sternum. Use your hands to press down on both sides to pop open the rib cage and then flip it over and press down firmly to flatten the breasts out.
To a separate small bowl, add the softened butter, minced garlic, chopped fresh herbs, cayenne, salt and pepper. Mix to combine well. Spread the butter mixture evenly over the turkey breast.
Preheat the air fryer to 350ºF.
For boneless turkey breast: Place the seasoned turkey breast skin side down and cook for 15 minutes. Using tongs, flip the turkey breast over and continue air frying for 20 minutes or until the internal temperature reaches 160ºF.
For bone-in turkey breast: Cook skin side down for 30 minutes. Carefully flip the turkey breast over and continue air frying for another 30-45 minutes or until the internal temperature reaches 160ºF. If the top begins to darken too quickly, place a small sheet of aluminum foil on top.
Remove from the air fryer, tent with foil and allow to rest for at least 10 minutes before slices.