Refrigerate chicken overnight in 2 cups of buttermilk.
Remove chicken from buttermilk and let rest outside the fridge for 30 minutes before preparing to fry.
Mix flour, salt, pepper, thyme, paprika, cayenne, garlic powder, and onion powder until evenly combined.
Combine milk and 1/8 cup buttermilk in a small bowl.
Pour the milk mixture into the flour and mix with a fork until lumps form.
Sprinkle each piece of chicken with a little salt and pepper, then coat with the flour mix by pressing the mix onto the chicken to ensure it adheres.
In a deep skillet or Dutch oven, heat 2 inches of oil to 350 F.
Cook meat in batches to avoid overcrowding the pan. Cook until edges golden brown and flip, about 10-15 minutes). Cook on other side for 10 minutes. Juices should run clear when meat is cooked thoroughly.
Let cool and drain on wire rack.