Prep the chicken: Pat the chicken pieces dry with paper towels. Dry chicken helps the coating stick and crisp up better.
Whisk the wet mix: In a medium bowl, whisk the egg, Dijon (if using), and olive oil until smooth.
Add the chicken and toss to coat.
Mix the coating: In a shallow dish, combine Parmesan, breadcrumbs, cornstarch, garlic powder, paprika, Italian seasoning, onion powder, salt, and pepper. Stir well so the flavors are evenly distributed.
Coat the bites: Lift chicken from the egg mixture, let excess drip, then roll each piece in the Parmesan breadcrumb mix. Press gently so the coating adheres.
Preheat the air fryer: Heat to 390°F (200°C) for 3–5 minutes.
A hot basket gives you a better sear right away.
Arrange and mist: Lightly mist the air fryer basket with oil. Place chicken bites in a single layer with a bit of space between them. Lightly mist the tops too.
Work in batches if needed.
Air fry: Cook for 8–10 minutes, shaking the basket or flipping halfway. Aim for internal temp of 165°F (74°C). The coating should be golden with crisp edges.
Finish and serve: Squeeze a little lemon over the hot bites for brightness.
Garnish with parsley if you like. Serve with your favorite dip.