Dark brown sugar and a dollop of whipped cream give this warm drink a deep, rich flavor.

• In a small bowl, stir the sugar, oil, zest, vanilla, and allspice until combined.
• Bring a kettle of water to a boil; you’ll need ½ cup of water for each drink. Fill mugs or heatproof glasses with hot tap water to warm them. Once the water in the kettle boils, empty the warm mugs and fill each with ½ cup boiling water and ¼ cup rum. Stir a generous tablespoon of the spiced oil into each mug until melted. Garnish with a small dollop of whipped cream.