Because we make this easy green bean casserole without mushroom soup, it’s unlikely to come out soupy like other soup-based versions. However, if you want to reduce the casserole sauce, you may cook it longer, let it sit longer, or drain excess sauce before serving. You might also consider adding breadcrumbs on top of your casserole, as this addition will soak up some of the liquid from the mixture, eliminating unwanted soupiness.