Rinse coffee mug with hot water and then add brown sugar syrup* and Kilbeggan<sup>®</sup> whiskey. Fill mug with coffee. Lightly whip heavy cream and pour gently into the mug over the back of a spoon. Garnish with freshly grated nutmeg.
*To make brown sugar syrup, combine 2 parts brown sugar and 1 part water in a saucepan over medium heat. Stir occasionally until sugar is completely dissolved. Remove from burner and let cool. Store refrigerated in an airtight container for up to 3 weeks.