Using a sharp knife, carefully pierce the chicken pieces. Submerge the chicken in a brine made from milk (or water), salt, garlic, peppercorns, and bay leaves. Let it soak for 2–3 hours, or preferably overnight for optimal tenderness and flavor penetration.
In a large bowl, whisk together the flour, cornstarch, kosher salt, white pepper, black pepper, garlic powder, onion powder, cayenne pepper, and baking powder until thoroughly combined.
Take 1 cup from the prepared seasoning mix and combine it in a separate bowl with cold water. Stir until a smooth, lump-free batter forms.
After removing the chicken from the brine, spoon a few tablespoons of the brine into the dry seasoning mix. Use your hands to incorporate the liquid, forming small clumps and rough bits—these will enhance the texture of the crust.
Dip each piece of chicken into the wet batter, allowing excess to drip off. Immediately coat the chicken in the dry seasoning mixture, pressing the mix firmly onto the surface to ensure full coverage. Set the coated chicken aside on a baking tray while preparing the oil.
In a heavy-bottomed pot, cast iron skillet, or Dutch oven, heat neutral oil to 350°F. Fry the chicken in batches for approximately 8–12 minutes, depending on the size of each piece, until the internal temperature registers at least 165°F.