Melty Nutritional Yeast ‘Cheese’

1 cup nutritional yeast (recipe recommends Good Tasting Nutritional Yeast)
1/3 cup all-purpose flour
3 Tbsp. cornstarch
1 1/2 Tbsp. salt
2 cup water
1/4-1/2 cup margarine
2 tsp. prepared mustard (optional)

• Mix dry ingredients in a sauce pan.
• Gradually add water, making it into a smooth paste and then thinning with the remaining water.
• Place over heat and stir constantly until it thickens and bubbles. Let it bubble for about 30 seconds, then remove from heat.
• Whip in the margarine (and mustard if desired).