With a mixer, whip 2 tbsp. cream until thick; set aside. Combine the remaining cream, the sugar if using, molasses, and pumpkin pie spice in a small saucepan. Whisk over medium-low heat until steaming and well blended, about 3 minutes.
Remove from heat, stir in hot coffee, whiskey, and liqueur. Pour into two mugs. Add a cinnamon stick and top with a dollop of whipped cream.
*Find at well-stocked grocery or liquor stores.