Chef John's Hot Buttered Rum

Details

Ingredients

• 8 tablespoons unsalted butter, at room temperature
• ½ cup firmly packed dark brown sugar
• ¼ teaspoon pure vanilla extract
• ½ teaspoon ground cinnamon
• ⅛ teaspoon ground ginger
• ¼ teaspoon ground nutmeg
• ⅛ teaspoon ground cardamom
• 1 pinch ground cloves
• 1 pinch salt
• 6 tablespoons heavy cream
• 1 ⅛ cups dark rum
• 4 ½ cups boiling water, or as needed
• ⅛ teaspoon ground nutmeg, or to taste