Make a cut at the joint of each chicken leg quarter about 1/2 through to speed up cooking. Season pieces with salt and pepper. Place the butter in a shallow baking dish large enough to hold the chicken pieces in a single layer. Melt under the broiler, then remove from the oven. Place chicken in pan and turn to coat all pieces with the melted butter.
Arrange chicken skin side up. Cook under broiler about 7 minutes on each side. Baste the chicken with the butter.
Combine the mustard, 1 tablespoon wine, and cayenne. Brush over chicken and sprinkle 1 tablespoon bread crumbs over chicken. Reduce heat to 450 degrees F. Bake chicken 10 minutes.
Turn chicken and baste with remaining mustard mixture and sprinkle with remaining bread crumbs. Bake another 15 minutes. Remove chicken pieces to a serving platter. Add remaining wine to pan and stir to loosen any particles stuck to the bottom. Add parsley and spoon sauce over chicken.