To make this Herbed Mushroom Spoon Bread Recipe gluten free, verify that the cornmeal is certified gluten free and not processed in a facility with wheat. Confirm that the baking powder, broth, sour cream, heavy cream, Swiss cheese, and seasonings are labeled gluten free. Use vegetable broth or chicken broth that is certified gluten free. Prepare the recipe with clean cookware, utensils, and a clean baking dish to prevent cross-contact with gluten-containing foods.