Preheat oven to 375°. In a small bowl, combine the sour cream and mustard. (If you are unable to find true Creole mustard, I've had success substituting a mixture of Dijon and yellow mustard with a few drops of Tabasco sauce.) In another bowl, mix together the cornbread crumbs and seasonings. Spread the mustard mixture over the chicken pieces, then roll the chicken in the crumb mixture. Arrange the chicken in a single layer in a large, shallow baking dish and drizzle with the melted butter. Bake at 375° until the chicken is golden brown and the juices run clear if tested with the tip of a knife, usually a little over an hour.