So I have been experimenting with different vegan cheese sauces, I used to fall back on a very simple one - in fact, I fed the very simple one well spiced over pasta on a backpacking trip to two meat eaters and they enjoyed it - that was based in a flour and oil roux, soy milk, nutritional yeast, and salt (with any variety of spices added, to taste or type of dish).
I tried a potato/carrot one my roommate made last semester, so decided to make my own by putting together different vegan recipes on the internet. My favorite is four small potatoes peeled, two carrots peeled, both boiled. Then blend well with 1/2 cup boiled veggie water, 1/2 cup well-soaked cashew pieces, 1/2 cup nutritional yeast, a spoonful of lemon juice, and a generous splash of both roasted tahini and oil. Season with garlic powder, onion powder, smoked paprika, and salt.
It's great over cooked broccoli with cracker crumbs, like a simple casserole.
Last night I mixed it with marinara sauce on my pasta and it was excellent!
I'm thinking about trying to make "broccoli cheese" soup with it, maybe adding a cup or so of plain almond or soy milk, and blending cooked broccoli in it. I dunno.