To make this recipe gluten free, use a certified gluten-free flatbread, naan, or pizza crust. Verify that the BBQ sauce, cooked chicken, Gouda cheese, red pepper flakes, and all packaged ingredients are certified gluten free. If using rotisserie chicken, check the label carefully, as some seasonings or marinades may contain gluten. Prepare the flatbread on a clean baking sheet with fresh parchment paper to prevent cross-contact.