I sprinkle it on post cooking. It doesn't need to be cooked at all and I'm not sure it should be.
I use Bragg's nutritional yeast. I found it at my local supermarket in their health foods specialty section.
The Nutritional Facts from the jar has it 20 calories for 1 Tbsp, 2 grams protein and 1 gram fiber.
It's interesting alright. The most intriguing thing is the flavor. Almost cheese-like and 1 teaspoon packs plenty of flavor. The stuff can easily become addictive. I use it on microwaved sweet potatoes as well, along with some non fat sour cream. I'm still discovering uses for it. Give it a shot. If you like the flavor of a medium flavored cheese, this should be a winner. But this has zero fat and only 1 gram carb in the 20 calories.