Prepare the Marinade:

• In a mixing bowl, combine the whole-grain mustard, olive oil, honey (if using), garlic powder, paprika, salt, and black pepper. Stir until well blended.

Marinate the Chicken:

• Pat the chicken breasts dry with paper towels to remove excess moisture.
• Place the chicken breasts in a resealable plastic bag or a shallow dish. Pour the mustard marinade over the chicken, ensuring all pieces are well coated.
• Seal the bag or cover the dish and refrigerate for at least 30 minutes to allow the flavors to meld.

Preheat the Air Fryer:

• Preheat the air fryer to 375°F (190°C) for about 5 minutes.

Cook the Chicken:

• Lightly spray the air fryer basket with non-stick cooking spray to prevent sticking.
• Place the marinated chicken breasts in the air fryer basket in a single layer, ensuring they are not overcrowded.
• Air fry the chicken at 375°F (190°C) for 10 minutes.
• After 10 minutes, flip the chicken breasts to ensure even cooking. Continue to air fry for an additional 6–9 minutes, or until the internal temperature reaches 165°F (74°C).

Rest and Serve:

• Once cooked, remove the chicken breasts from the air fryer and let them rest on a cutting board for about 5 minutes before slicing.
• Serve the chicken breasts whole or sliced, paired with your choice of sides.