Can I substitute something for the nutritional yeast or leave it out? I have never used it and I don't know what it does in a recipe. Thanks.

Hi Nancy! If you haven't cooked with nutritional yeast, I highly recommend trying it out. I always have a bag in my pantry and use it as a seasoning in tons of recipes (stirred into soup or salad dressing, sprinkled on roasted vegetables or popcorn, etc). It adds lots of umami and an awesome cheesy flavor. Here's a quick explainer on the ingredient to learn more: https://food52.com/blog/12461-nutritional-yeast-better-than-cheese.