Gently pour 2 cups apple cider into medium-size pot; add ¼ cup unsalted butter, ¼ cup lightly packed brown sugar, 3 cinnamon sticks, ¾ tsp nutmeg, 4 whole cardamom pods and ¼ tsp salt. Bring to a gentle boil over medium-high heat. Reduce heat and simmer, stirring occasionally, for 15 minutes. Remove from heat and stir in ⅔ cup dark rum. Serve hot in espresso cups or small mugs.
Recipe adapted from: Luxmore, Crystal and Tara. "Hot Buttered Rum Cider." Food & Drink. Autumn 2017.