Make the pumpkin spice syrup by combining pumpkin purée, sugar, water, and pumpkin pie spice in a small saucepan.
Bring the mixture to a simmer over medium heat, stirring until sugar dissolves.
Simmer for 5 minutes until the syrup thickens slightly, then remove from heat and stir in vanilla extract.
Let the syrup cool completely before use.
Fill a glass with ice cubes and add 2–3 tablespoons of the pumpkin spice syrup.
Pour in the milk and espresso or strong brewed coffee.
Stir well to combine all ingredients.
Top with whipped cream if desired and sprinkle with a little cinnamon or pumpkin pie spice for garnish.
Serve immediately and enjoy your homemade fall latte!