Pat dry the chicken breasts with a paper towel and, with a sharp knife, cut them into 1-inch, nugget-sized pieces.
In a medium bowl, large enough to fit the nuggets, whisk the egg with the milk. Add the chicken nuggets into the bowl and toss them around to coat them with the wet mixture.
In a gallon-sized zip bag, combine the flour and seasonings. With a fork or kitchen tongs, transfer the nuggets from the bowl into the zip bag containing the seasoned flour. Once all the nuggets are in the bag, seal the bag closed and shake the bag to coat them well. Use your hands to press the coating into the nuggets so they have a thicker and crispier crust.
Prep:
Preheat the air fryer at 400F for 5 minutes. Starting with a hot basket ensures even heating and crisper exteriors.
Cook:
Place the breaded chicken nuggets in a single layer in your air fryer basket on top of the wire rack. Don't stack them, and if necessary, do this process in two batches.
Air fry them at 400F for 12 minutes until the internal temperature of the thickest nugget is 165F. If necessary, remove the smaller pieces and add 1-2 minutes of cooking time to the thicker pieces. If you use an air fryer liner, you'll definitely want to flip them over to get them nice and golden on both sides.
Serve:
Remove the cooked chicken nuggets from the air fryer using kitchen tongs and serve them warm with your favorite dips.