To make this recipe gluten free, replace the bread with certified gluten-free bread or gluten-free breadcrumbs, and use a gluten-free cream of onion soup or homemade onion gravy base. Also confirm that the Worcestershire sauce, beef bouillon powder, and all packaged ingredients are labeled gluten free or free from cross-contact concerns, since some brands may contain hidden gluten. If preparing in a shared kitchen, use clean cookware, utensils, and prep surfaces to help avoid gluten contamination.