• 1 stick (4 ounces) unsalted butter
• ½ cup light brown sugar
• 1 teaspoon vanilla extract
• 1 teaspoon ground cinnamon
• 1 teaspoon ground nutmeg
• 1 teaspoon ground allspice
• Pinch of salt
• 2 ounces dark or aged rum
• 6 ounces hot water
• Cinnamon stick, for garnish (optional)