In a large bowl, combine the buttermilk and beaten egg. Add the chicken pieces, ensuring they are fully submerged in the marinade. Cover and refrigerate for at least 4 hours, or overnight for the best flavor and tenderness.
In another bowl, whisk together the flour, paprika, garlic powder, ground white pepper, celery salt, ground black pepper, dry ground mustard, kosher salt, onion powder, thyme, basil, oregano, ginger, and MSG if using.
In a deep fryer or heavy pot, heat about 3 inches of vegetable oil to 350°F (175°C).
Remove the chicken from the marinade, allowing excess buttermilk to drip off. Dredge each piece in the flour mixture, ensuring an even coating.
Carefully place the coated chicken pieces in the hot oil, making sure not to overcrowd the pot. Fry until golden brown and an internal temperature of 165°F (75°C) is reached, about 12-15 minutes per side.
Once cooked, transfer the chicken to a wire rack set over a baking sheet. Let it rest for a few minutes to allow the excess oil to drain.
Serve your homemade Kentucky Fried Chicken hot, perhaps with a side of coleslaw and mashed potatoes.