Prepare the chicken by patting dry and pounding to an even thickness. Season both sides with salt, pepper, and garlic powder.
Make the glaze by combining maple syrup, soy sauce, and Dijon mustard in a saucepan. Simmer for 5-7 minutes until thickened.
Preheat the air fryer to 375°F (190°C). Lightly spray the basket and place the chicken inside without overcrowding. Cook for 8-10 minutes, flip, then cook for another 5-7 minutes until internal temperature reaches 165°F (74°C). Let rest for 3-5 minutes.
Brush the thickened glaze over each chicken breast and return to the air fryer for an additional 2-3 minutes until sticky and caramelized.