Pat chicken dry with paper towels. Combine mustard, garlic powder, and salt in a small bowl and sprinkle evenly over chicken. Combine flour and baking powder in a shallow dish and, working one piece at a time, dredge chicken parts until well coated, shaking off excess. Refrigerate for 30 mins (or up to 2 hours).
To Freeze: Freeze in freezer safe container
To Reheat: Fully defrost. Heat peanut oil in a Dutch oven or large pot over medium-high heat. Cover and cook until well browned, about 5 minutes per side. Lower temperature to medium, continue cooking uncovered, turning as necessary to cook chicken through, about another 5 mins per side. Set chicken on a wire rack over cookie sheet, sprinkle with Old Bay Seasoning.