Well, I'm not sure as I don't cook. I asked Jebra but he doesn't use cashew milk and doesn't know either. If you usually substitute cashew milk for cream, I think I'd try it with this recipe as well. As for the cornstarch, I'd hold off on that unless the potatoes seem way too thin and then add a bit at the end. The texture of stoemp is very much like that of normal old mashed potatoes.