To make these Chocolate Peanut Butter Cookies gluten free, replace the all-purpose flour with a reliable 1:1 gluten-free baking flour blend that includes xanthan gum or a similar binder. Also confirm that the cocoa powder, powdered sugar, vanilla extract, baking soda, and peanut butter are labeled gluten free, since some brands may vary or be processed in shared facilities. If your gluten-free flour blend does not already contain a binder, you may need to add a small amount of xanthan gum to help the dough hold together around the peanut butter filling. For anyone with celiac disease or severe gluten sensitivity, use clean bowls, parchment, baking sheets, mixers, and utensils to avoid cross-contact.