Marinate the chicken: In a large mixing bowl, add buttermilk, salt and pepper. Mix well and add chicken. Cover with plastic wrap and marinate the chicken in the refrigerator for 3 hours.
Make the dredging mix: In a large mixing bowl, combine flour, cornstarch, garlic powder, oregano, white pepper, cayenne pepper, paprika and salt. Mix well and set aside.
Fry the chicken: When ready to cook, place a deep fryer or large pot over medium-high heat and add 2 inches of oil. Heat the oil to 350˚F (177˚C).
Working one at a time, remove each chicken piece from the marinade. Shake to remove excess, and then place it in the dredging mix and coat thoroughly. Tap off the excess.
Slowly lower the breaded chicken pieces into the oil with a slotted spoon. You’ll notice that the temperature will drop slightly, so adjust the heat so that the temperature will stay between 300-350˚F.
Fry each piece for about 10-15 minutes, turning each piece every 2 minutes, until the chicken reaches an internal temperature of 165˚F.
Remove the chicken from the oil and place on a cooling rack. Let them rest for 10 minutes.
Assemble the sandwich: Place one donut on a plate, then add the crispy chicken on top. Add another donut on top. Serve hot and enjoy!