In a food processor or high speed blender process the pistachios until they become finely ground. Set the ground pistachios aside on a plate.
Wipe down the processor or blender and add the rest of the ingredients, blending until well combined. This will be sticky and you may need to scrape down sides and stir things around a few times.
Once complete, wet your hands a little and form the truffles - they should be slightly smaller than ping pong balls.
Roll into the ground pistachios and place in the fridge. They will firm up and be ready to enjoy after about 2 hours. Keep in the fridge or freezer!