In a mixing glass, add the bourbon, pumpkin puree, maple syrup, and bitters. Use a muddler or the back of a spoon to gently muddle the pumpkin puree with the other ingredients.
Fill the mixing glass with ice and stir in the mixture well to chill the ingredients.
Strain the mixture into a rocks glass filled with ice.
Garnish with a cinnamon stick for a festive touch.