Pat the chicken pieces dry with paper towels.
In a large, shallow bowl, whisk together the all-purpose flour, cornstarch, salt, black pepper, white pepper, paprika, garlic powder, onion powder, dried thyme, and cayenne pepper.
In another shallow bowl, whisk the eggs with the whole milk until smooth.
Dip each chicken piece into the egg mixture, letting any excess drip off, then press it into the seasoned flour to coat completely.
Return the coated chicken to the egg mixture for a quick second dip, then coat again in the flour mixture, pressing to adhere. Arrange the coated pieces on a wire rack.
Heat about 4 cups of vegetable oil in a deep, heavy-bottomed skillet or deep fryer to 350°F (175°C).
Working in batches, carefully lower 3–4 chicken pieces into the hot oil without overcrowding. Fry for 8–10 minutes per side, turning occasionally, until golden brown and cooked through (internal temperature 165°F/74°C).
Transfer the fried chicken to a wire rack set over a baking sheet to drain any excess oil.
Repeat with the remaining chicken pieces.
Serve hot with fries, coleslaw, or a simple green salad.