Pierce each piece of chicken gently with a knife. Submerge in a brine made of whole milk (or water), salt, garlic cloves, black peppercorns, and bay leaves. Let soak for 2 to 3 hours, or overnight for deeper flavor and tenderness.
Mix together the flour, cornstarch, kosher salt, white pepper, black pepper, garlic powder, onion powder, cayenne pepper, and baking powder in a large bowl until evenly combined.
Take 1 cup of the seasoning mixture and stir it into a separate bowl with cold water until a smooth wet batter forms.
Remove the chicken from the brine. Add a few spoonfuls of the brine to the remaining dry seasoning mix, using your hands to mix and form small lumps for enhanced texture.
Dip each piece of chicken into the wet batter, allowing the excess to drip off, then press it into the dry seasoning mixture until thoroughly coated. Set the coated pieces aside on a baking tray.
Heat neutral oil in a large cast iron skillet, Dutch oven, or heavy-bottomed pan to 350°F. Fry the chicken for 8 to 12 minutes, depending on size, until the internal temperature reaches 165°F.