Pour the sugar-free vanilla syrup into the bottom of a warm mug.
Pull a double shot of espresso. Add it to the mug. Starbucks uses its blonde espresso blend, but you can substitute with any other beans.
Begin steaming the non-fat milk with the steam wand on your espresso machine. If you don't have a steam wand, heat the milk in a saucepan on the stove while aerating it with a frother or whisking until it becomes hot and frothy.
Pour the steamed milk over the syrup and espresso, leaving a little room at the top for the foam.
If you like foam, spoon a bit of foam on top of the latte. Most lattes are made using minimal foam, but you should always follow what tastes right to you.
If desired, sprinkle some cinnamon on top for extra flavor.