In a medium saucepan, combine milk or a non-dairy alternative, cannamilk, and Nutella. Set the stove on medium heat and whisk vigorously until the liquid is steaming and hot but not boiling. Once it reaches this point, remove from the heat.
Pour the hot cocoa in mugs and top the cups off with whipped cream, marshmallows, chocolate syrup drizzle and hazelnuts for an added garnish.