I got this idea from a TV show about rationed cooking, combined with my experiments making a non-cheese based creamy sauce. It is very cheap and simple but surprisingly rich and tasty when finished.
YEAST EXTRACT is marmite or vegemite. For some reason it won't let me add it to the ingredients. You need 2 teaspoonfuls for this recipe. A strong veg buillion powder could be subsituted, but would change the taste a bit.