To make this Almond Joy Tart gluten free, replace the all-purpose flour in the tart dough with a high-quality 1:1 gluten-free baking flour blend that contains xanthan gum or add xanthan gum if your blend does not already include it. Be aware that gluten-free tart dough can be more delicate and may crack more easily when rolled, so it may help to roll the dough between sheets of parchment paper or press it directly into the tart pans by hand. In addition, confirm that the white chocolate, milk chocolate, dark chocolate, shredded coconut, and any other packaged ingredients are labeled gluten free, since some brands may have additives or cross-contact concerns.