Spicy Southern-Fried Chicken

Buttermilk Marinade: In a gallon-sized sealable plastic bag or a large bowl with a tight-fitting lid, combine the buttermilk, mustard, salt, dry mustard, cayenne, and black pepper. Add the chicken pieces and turn to coat. Seal and refrigerate for at least 2 hours or overnight. Frying the chicken: Preheat oven to 150 degrees F. In a 13-inch by 9-inch by 2-inch pan, whisk together flour, baking powder, dry garlic, and salt. Add chicken pieces and turn to coat thickly. Let the chicken stand 10 minutes, turning occasionally to recoat with flour. Shake off excess flour before frying.