Prepare the Chicken: Cut the boneless, skinless chicken breasts into bite-sized pieces, approximately 1-inch cubes.

Marinate the Chicken: In a bowl, mix the buttermilk, garlic powder, onion powder, paprika, salt, and black pepper. Add the chicken pieces to this mixture, ensuring they are well-coated. Cover the bowl and refrigerate for at least 30 minutes, allowing the chicken to absorb the flavors.

Prepare the Coating: In another bowl, combine the all-purpose flour, cornstarch, baking powder, and a pinch of salt. Mix well to ensure an even coating mixture.

Coat the Chicken: Remove the chicken from the marinade, letting the excess buttermilk drip off. Dredge each piece in the flour mixture, pressing down slightly to ensure a good coating. Place the coated pieces on a plate.

Heat the Oil: Pour vegetable oil into a deep frying pan, about 2 inches deep. Heat the oil to 350°F (175°C), which is the ideal temperature for frying.

Fry the Chicken: Fry the chicken in batches, ensuring not to overcrowd the pan. Fry each batch for 5-6 minutes or until golden brown and crispy. Use a slotted spoon to remove the chicken from the oil, and place it on a paper towel-lined plate to drain excess oil.

Serve: Serve the crispy popcorn chicken hot, with your favorite dipping sauce or as part of a larger meal.