To prepare this recipe gluten-free, substitute the breadcrumbs with a certified gluten-free alternative such as crushed gluten-free crackers, oats, or gluten-free panko. Additionally, replace the all-purpose flour in the sauce with a gluten-free flour blend or cornstarch (1:1 ratio) to thicken. Be sure all packaged ingredients, such as Parmesan or chicken, are verified gluten-free.