Place the chicken breasts onto a cutting board and with a meat mallet, flatten each into even thickness.
Then, cut each breast in half.
Sprinkle the chicken pieces with salt and black pepper and set aside.
In a blender, add the oats, mustard powder ,parsley, salt and black pepper and pulse until a coarse breadcrumb-like mixture is formed.
Transfer the oat mixture into a shallow bowl.
In another bowl, crack the eggs and beat well.
Coat the chicken pieces with oats mixture and then, dip into beaten eggs and again, coat with the oats mixture.
Grease the Air Fryer Basket with cooking spray and then slide inside.
Adjust the temperature of Air Fryer to 350 °F to preheat for 5 minutes.
After preheating, arrange the chicken pieces into the greased Air Fryer Basket in a single layer.
Slide the basket into Air Fryer and set the time for 12 minutes.
While cooking, flip the chicken pieces once halfway through.
After cooking time is finished, remove the chicken pieces from Air Fryer and serve.