Blend or whisk together and place in the fridge. The mix gets very thick as it gets cold, almost solidifying. You may need to mix it once or twice to get a uniform mixture.
Nutritional yeast can be purchased at most health food stores. It should not be confused with baker's yeast or brewer's yeast which are very different. Be sure to find a brand and package size that is not cross contaminated with your allergens.
The yeast flakes add a sort of buttery/cheesey flavor and it spreads on smooth.