The instruction to chill the pastry dough for an hour is one of the most important steps in this entire crostata recipe. This resting period in the refrigerator is where the magic happens, transforming a soft, sticky dough into a firm, workable pastry that will bake up perfectly crisp and crumbly.
First, chilling the dough re-solidifies the butter. When you mix the dough, the butter softens. If you try to roll out a warm dough, the butter will make it sticky and difficult to handle. A chilled dough, with its firm, cold butter, is much easier to roll out evenly without sticking. More importantly, when the cold butter hits the hot oven, it melts and creates steam, which results in a lighter, flakier, and more tender crust.
Second, chilling allows the gluten to relax. The moment you add liquid to flour, gluten begins to form. Even the minimal mixing and kneading in this recipe will develop some gluten strands. Letting the dough rest in the fridge allows these strands to relax, much like resting a muscle after exercise. A relaxed dough is less likely to shrink or become tough when baked.
Finally, the chilling period helps to hydrate the flour. It gives the flour particles time to fully absorb the liquid from the eggs, which results in a more uniform texture and better flavor in the final baked product.
This hour of “inactive” time is, in fact, one of the most active and transformative stages in the pastry-making process. It is the key to achieving the fabulous, crumbly, melt-in-your-mouth texture that makes this crostata so special.