Peel and quart potatoes. Boil in large pot filled with water until tender. Drain potatoes then mash to desired consistency.
In a large pot set over medium heat melt dairy-free butter. Add in chopped onions and garlic. Cook about 5 minutes, stirring frequently.
Stir in starch/flour then whisk continuously; about 3 minutes.
Carefully stir in Silk® Original Almondmilk a little at a time. Whisk well with each addition until gone.
Stir in salt, pepper, red pepper flakes. and ground mustard.
Cook soup for 10 minutes, stirring occasionally.
Whisk in mashed potatoes then stir to combe well.
Stir in vegan cheese shreds and green onions.
Serve in soup bowls.