To make this Cheesy Chicken Manicotti Recipe gluten free, use certified gluten-free manicotti pasta if available. If gluten-free manicotti is difficult to find, gluten-free jumbo pasta shells can be used as an alternative. Also make sure the marinara sauce, seasonings, and shredded chicken are all labeled gluten free, since hidden gluten can sometimes show up in packaged ingredients. Use clean utensils and cookware if you are cooking for someone with celiac disease or a strong gluten sensitivity to avoid cross-contact.