Add plenty of ice to a large drinking glass (about the size of a pint glass). Pour 1/2 tbsp pumpkin spice syrup over the ice, then pour cold brew over ice. Set aside.
Add milk of choice and 1 tbsp of pumpkin spice syrup to a small cup. Using a milk frother, whisk until the milk foams up and approximately doubles in size.
Pour cold foam over the cold brew. To keep the layers separated as much as possible, pour the cold foam over a spoon directly over the cold brew. (This will minimize the amount of immediate mixing of the cold foam and cold brew.) Top with pumpkin pie spice and serve.
I didn't include nutrition info here since it will depend heavily on the milk that you use. See below for the nutrition info and scannable My Fitness Pal barcode for the Pumpkin Spice Syrup.