Preheat the oven to 400 degrees F. Fit a sheet tray with a wire rack and spray with nonstick cooking spray.
Mix together buttermilk, lemon juice, hot sauce, onion, thyme, garlic, salt, and pepper to a large bowl. Add chicken and coat with mixture. Cover with plastic wrap and place in the refrigerator for 3 hours or up 12 hours.
Mix corn flakes, Parmesan cheese, and thyme together. Season with salt and pepper.
Remove chicken from the marinade, letting the excess drip off, and dredge through the corn flake-Parmesan mixture, pressing to help it adhere.
Place on the wire rack-fitted sheet tray and bake for 45 minutes until golden and crisp.
Cook's Note: Remove the skin to save calories. Soaking chicken in buttermilk leaves the chicken incredibly moist with a delicious flavor.