My conditional answer is yes. Since butter is an integral part of the flavor profile, make sure that whatever butter substitute you use tastes a good bit like real butter. Try Melt, Country Crock Plant Butter, or Earth Balance sticks. Make sure your sugar is vegan as well, and swap out the dairy for plant-based milk. Since we're thickening the base with cornstarch, make sure that whatever plant-based milk you use will withstand boiling without separating.