Whisk buttermilk, mustard, 2 tsp salt, 1 tsp garlic powder, 1 tsp black pepper and hot sauce together in a bowl. Add chicken, turn to coat well, cover and refrigerate at least 1 hour or overnight.
Toss cornflakes, bread crumbs and remaining 1/2 tsp of garlic powder, remaining 1/2 tsp black pepper, remaining 1/4 tsp salt, poultry seasoning, paprika, and cayenne in a zip top gallon bag.
To Freeze: Freeze in freezer safe container
To Reheat: Completely defrost chicken. Heat oven to 400 degrees. Cover cookie sheet in foil. Place wire rack on top and spray with nonstick spray. Place breading mixture in a bowl and drizzle 2 Tbsp oil over crumbs. Toss until well coated. Dredge chicken in crumb mixture and place on prepared rack. Bake 35-40 mins.