In a small bowl, mix together the butter, crushed fennel seeds, rosemary, sage, orange zest, garlic, 1 teaspoon of salt and pepper.
Place the turkey on a clean work surface and pat it dry with paper towels.
Loosen the turkey skin by sliding your fingers underneath and gently lifting it off the meat. Start near the cavity where the skin is looser and work your way around the entire breast.
Insert the butter mixture into these pockets and press it into the meat.
Sprinkle the remaining ½ teaspoon of salt all over the surface of the skin.
Pour ½ cup of broth into the bottom drawer of the air fryer basket.
Place the turkey skin side/breast side up in the basket. Air fry at 350F for 25 minutes.
Carefully flip the turkey breast over and air fry for another 25 minutes.
Flip the turkey back over to breast side up and air fry for another 10-15 minutes, or until an instant read thermometer reads 165F.
Remove from air fryer and let rest on a cutting board for 10-15 minutes before carving.
Make the gravy:
Carefully lift the crisping plate off the air fryer drawer. Pour the drippings into a 2-cup measuring cup. (You can strain it first if you prefer). Add enough broth to the measuring cup to bring it to 1 ½ cups.
In a small saucepan over medium heat, melt the 2 tablespoons of butter. Once bubbling, add in the flour and whisk constantly for at least a minute. The roux should be a smooth, golden paste.
Slowly pour in the drippings/broth mixture, whisking vigorously as you pour. Once bubbles start to form, reduce the heat to low and let simmer for 3-5 minutes, stirring constantly so it doesn't burn on the saucepan. The gravy will thicken as it simmers.
Notes
Air fryer size. To fit a 5 pound turkey breast, an extra large basket-style air fryer works best (so anything from 5.5 - 8 quart). My air fryer is 5.8 quart and a 5 pound turkey was the maximum it could hold. I haven't tested this recipe in a toaster oven style air fryer.
Clearance height. Turkeys vary is shape, so you'll want to make sure it fits in your basket and there is space between the top of the turkey and the top heating element in the air fryer. Make sure there is about an inch of clearance as the turkey will plump up as it air fries. If the turkey touches the top heating element, it will burn quickly and may cause your air fryer to smoke.
Crushing fennel seeds. You can add the seeds to a resealable bag and use a rolling pin to crush them, but if you have a coffee grinder or small blender, that's the quickest way to crush them.
Surface prep. Make sure you pat the surface of the turkey skin dry with a paper towel. This absorbs moisture and helps the skin crisp up.
Add liquid to drawer. Adding broth or water to the bottom drawer of your basket style air fryer will catch the turkey drippings and prevent them from burning onto the bottom of the drawer.
Thermometer is essential. I always use an instant read thermometer to make sure the thickest part of the turkey breast has reached 165F.
Breast side up. I recommend starting with the turkey breast skin side up in the air fryer. This differs from a lot of recipes. I like to brown up the skin first, and then flip it over. But, I still finish with the breast side up to ensure it's super crisp.
Resting period. Letting the turkey breast sit for 10-15 minutes before carving allows the juices to redistribute. Don't tent the turkey with foil during this time. This just makes the skin soggy.