01 -  Preheat oven to 325°F. Position a rack in the lower third of the oven. 
 02 -  Score the surface of the ham in a diamond pattern with a sharp knife. Insert whole cloves at the intersections if desired. 
 03 -  Arrange the ham on a rack in a large roasting pan. Pour 1/2 cup water into the pan base to prevent burning. 
 04 -  In a small saucepan, combine root beer, brown sugar, Dijon mustard, apple cider vinegar, butter, black pepper, and cinnamon. Bring to a boil over medium-high heat, then reduce heat and simmer for 15–20 minutes, stirring occasionally, until reduced to about 1 cup and syrupy. 
 05 -  Generously brush the ham with some of the glaze. Cover loosely with foil and bake for 1 hour, basting with fresh glaze every 20 minutes. 
 06 -  Remove foil, raise oven temperature to 400°F, and continue roasting for 30–45 minutes, basting every 10 minutes until the surface is glossy and caramelized. 
 07 -  Allow ham to rest for 15 minutes before slicing. For a float effect, drizzle each slice with a touch of heavy cream and garnish with a maraschino cherry if desired.