To make these Christmas Linzer Cookies (Classic) gluten free, replace the all-purpose flour with a certified gluten-free 1:1 baking flour blend that contains xanthan gum. Also confirm that the almond flour, vanilla extract, powdered sugar, and jam are certified gluten free if needed for strict dietary requirements. Because gluten-free dough can be more delicate, chill it thoroughly before cutting and handle the cookies gently when transferring and assembling.