Place the chicken breasts between two sheets of plastic wrap and pound to even thickness.
Soak the 2 boneless chicken breasts   in 1 cup buttermilk  for at least 1 hour (or overnight for best flavor and tenderness).
In a shallow bowl, mix the 1 cup all-purpose flour  , ¼ cup cornstarch  , 1 teaspoon paprika  , g½ teaspoon garlic powder, ½ teaspoon salt and ¼ teaspoon black pepper.
In a separate bowl, whisk the 2 large eggs 
Remove chicken from the buttermilk and let excess drip off.
Dip each piece in the beaten eggs, then dredge in the flour mixture until fully coated.
Preheat your air fryer to 375°F (190°C) for 3 minutes.
Place chicken in a single layer in the basket (don’t overcrowd).
Air fry for 10–12 minutes, flipping halfway through, until golden brown and cooked to 165°F internally.
Lightly toast the 4 soft hamburger buns  in the air fryer for 1–2 minutes.
Spread ¼ cup mayonnaise  on each bun, then add 4 leaves lettuce   and the crispy chicken breast.
Serve warm and enjoy your homemade A&W Chubby Chicken Sandwich!