½ small pumpkin (preferably sugar pie variety) with stem, seeds, and strings removed (or skip this step and use ½ cup canned pure pumpkin purée)
½ cinnamon stick
1 cup water
2 cups granulated sugar
½ vanilla bean
½ tsp grated nutmeg
Roast the pumpkin in the oven at 400°F for about 20 minutes, or until soft enough to scoop its flesh away from the skin. While it is roasting, prepare the cinnamon: Use a mallet or small cast-iron pan to pound the cinnamon stick into smaller pieces. Toast the cinnamon in a pan over low heat for 30 to 60 seconds, or until fragrant.
Scoop out the soft flesh from the skin of the pumpkin and place the flesh in a blender or food processor along with the water, then purée until smooth. Transfer the pumpkin, cinnamon pieces, and sugar to a saucepan over medium heat and stir to dissolve the sugar.
Fillet open a vanilla bean and scrape the vanilla out using the tip of your knife. Add the vanilla to the pot. Add the nutmeg. Continue to cook the syrup at a simmer for 5 to 10 minutes over medium-low heat, stirring to incorporate the vanilla and nutmeg. Taste after 5 minutes, cook more if desired. When you are happy with the flavor, strain the syrup through a fine mesh strainer, pushing the pumpkin through with a rubber spatula. Discard the pulp and cinnamon pieces. Bottle the strained syrup in a clean container with a lid, and store in the refrigerator for up to 2 months.