Pour 1 cup of the soy milk into an ice cube tray and freeze for at least 4 hours, until solid.
Add the remaining 1/2 cup soy milk, protein powder, cocoa powder, maple syrup, vanilla and salt to a high speed blender. Blend for 15 seconds, until smooth with no dry pockets.
Pop out the frozen soy milk cubes and let them sit for 3 minutes to soften slightly. Add them to the blender and sprinkle the xanthan gum over the top.
Blend on high for 45 to 60 seconds, using the tamper or stopping to scrape down the sides, until thick, fluffy and spoonable like soft serve. Add a small splash of soy milk only if the blades get stuck.
Spoon into chilled glasses and serve right away with spoons. For the full viral experience, dip hot, salty fries straight into it.