To make this Chocolate Chip Cookie Pizza gluten-free, replace the all-purpose flour with a certified gluten-free 1:1 baking flour blend. Confirm that the cornstarch, baking soda, kosher salt, butter, sugars, vanilla extract, and milk chocolate chips are gluten-free and free from cross-contact. Some chocolate chips, baking powders, extracts, and packaged baking ingredients may be processed in facilities that handle wheat, so check labels carefully. Use clean mixing bowls, measuring tools, utensils, parchment paper, and a clean baking pan to prevent gluten contamination.