Prep the Chicken: Pat the chicken breasts dry with paper towels. Season both sides with salt, pepper, garlic powder, and smoked paprika.
Make the Glaze: In a small bowl, mix the whole grain mustard, olive oil, and honey until well combined.
Coat the Chicken: Brush the mustard glaze evenly over both sides of the chicken breasts.
Preheat the Air Fryer: Preheat your air fryer to 200°C (400°F) for 3 minutes.
Cook the Chicken: Place the chicken breasts in the air fryer basket in a single layer. Cook for 12-15 minutes, flipping halfway through, until the internal temperature reaches 74°C (165°F).
Rest and Serve: Let the chicken rest for 5 minutes before slicing. Garnish with fresh parsley if desired. Serve with your favorite sides like roasted vegetables, quinoa, or a fresh salad.