In a mixing bowl, combine the buttermilk, salt, black pepper, paprika, garlic powder, onion powder, and cayenne pepper. Whisk until well blended.
Add the chicken pieces to the buttermilk mixture, ensuring they are fully submerged. Cover and refrigerate for at least 30 minutes (or up to overnight) to marinate.
In a shallow dish, place the flour and season it with a pinch of salt and pepper. Mix well.
Heat the cooking oil in a frying pan or deep fryer over medium-high heat until it reaches 350°F (175°C).
Remove the chicken from the buttermilk marinade, allowing the excess to drip off. Dredge each piece in the seasoned flour until fully coated, pressing lightly to adhere.
Once the oil is hot, carefully place the breaded chicken nuggets in the pan. Fry in batches to avoid overcrowding, cooking for about 3-4 minutes per side, or until golden brown and cooked through.
Use tongs to transfer the cooked nuggets to a plate lined with paper towels to absorb excess oil.
Serve the nuggets warm with your choice of dipping sauce.