The method I detail in the recipe for folding or laminating the dough helps strengthen the pastry without overworking it. The dough is easy to roll out and won’t crack. If you use whole grain flour you may have to add more water as the whole grain will absorb more liquid than all-purpose flour. Whole-grain pastry is often drier and will crack more easily. I found through experience that using tapioca starch to thicken juicy fruit fillings works best to avoid the filling leaking out of galettes during baking. Making sure to brush eggwash between the folds also helps to seal the dough as it bakes and keeps it from cracking at the folds. That said the filling may bubble up and over the sides of the galette. If this happens I take it out of the oven and spoon up as much juice off the parchment paper as I can. Then add it back to the center of the galette and finish baking it. This is one reason I prefer to bake galettes on parchment paper.