Sprinkle the grill seasoning over the roast, making sure it is thoroughly seasoned. Place the crown roast into a roasting pan, bone ends up. Roast, uncovered, for 20 to 25 minutes per pound of meat, about 2 1/2 to 3 1/2 hours, or when the internal temperature is 150 degrees F. Make sure to baste with any pan drippings every 20 minutes for the first 2 hours. For the last hour of cooking, baste with the royal glaze. Wrap the bone ends with aluminum foil if they begin to brown too quickly.
While the roast is cooking, whisk together 1 cup chicken broth, mustard, Worcestershire sauce, 1/4 cup whiskey, garlic, ginger, and apple butter in a saucepan and place over medium-low heat. Let simmer until thick and reduced by a third, 12 to 15 minutes. Brush the glaze onto the roast every 15 minutes for the last hour of cooking.
Remove the roast from the oven, transfer to a serving platter, and let rest for 15 minutes before slicing. Garnish the platter with parsley.
Place the roasting pan over medium heat and deglaze with the remaining 1/2 cup whiskey, scraping up the bits with a flat edged spoon. Add the remaining royal glaze, remaining 1 1/2 cups chicken broth, and let simmer until thickened and reduced by half. Pour into a gravy boat and serve with the roast.