Add all ingredients (except the chopped pistachio) to a blender; put the lid on and let it sit for 2 minutes. (If your blender can’t take high temperature, put everything in a heat-safe bowl, cover the bowl, let it sit for 2 minutes, and then carefully pour it into a blender.)
Process until smooth and creamy (be careful, it’s hot!).
Pour into a small mug and sprinkle the pistachio on top; serve hot.
Notes
Cashews: Be sure to use raw, unsalted cashews here so their flavor doesn’t overwhelm the flavor of pistachio.
Recipe by An Edible Mosaic™ at https://www.anediblemosaic.com/thick-creamy-vanilla-pistachio-drink/