Marinate the chicken: In a shallow dish, mix the buttermilk, garlic powder, onion powder, paprika, salt, and pepper. Add the chicken breasts and let them marinate for at least 30 minutes, or up to overnight in the refrigerator.

Prepare the coating: In a separate shallow dish, combine the crushed cornflakes, shredded cheddar cheese, grated Parmesan, and flour. Stir until well combined.

Coat the chicken: Remove the chicken breasts from the buttermilk marinade and dredge them in the cornflake mixture, pressing lightly to ensure the coating sticks.

Cook the chicken: Heat olive oil in a large skillet over medium heat. Cook the coated chicken breasts for 5-7 minutes per side, or until golden brown and crispy, and the internal temperature reaches 165°F (75°C).

Serve: Once cooked, remove the chicken from the skillet and serve immediately.