Calabaza Nog

First you'll probably need to make the spiced pumpkin syrup:
Combine:
1 cup of brown sugar
1 cup of water
½ cup of pumpkin puree
1 tbsp each of nutmeg, ginger, allspice, cinnamon
Over medium heat until slightly thickened. Remove from the heat and place 1 vanilla pod into the syrup and chill overnight. Strain through a cheesecloth and store in a covered container, in a fridge, for up to one week.
Once the pumpkin syrup is ready, add all the ingredients except the bitters into a cocktail shaker with ice. Double shake before double straining into a cocktail glass. Add the bitters and garnish with some freshly shaven nutmeg,