In a small bowl, stir together the brown sugar, butter, nutmeg, cinnamon and cloves. Distribute evenly among 4 warmed mugs. Add 3 Tbs. rum to each mug, then fill with the boiling water, stirring well. Garnish with cinnamon sticks.
Adapted from Williams-Sonoma Outdoors Series, Snow Country Cooking, by Diane Rossen Worthington (Time-Life Books, 1999).