Why are tart shells docked before baking?

Docking tart shells before baking involves making small holes in the dough using a fork or a docking tool. This practice is essential primarily to prevent puffing and blistering during the baking process. When the tart shell is baked, steam is produced from moisture in the dough. If the steam cannot escape, it causes the dough to puff up or form blisters, which can result in an uneven texture and appearance.

By docking the dough, the steam has an escape route, allowing for a more consistent and flat tart shell. This technique is especially important for tart shells that will be filled and baked further, as a stable base is necessary for the integrity of the final dessert. The prevention of puffing and blistering ensures that the tart has a nice, even surface for any fillings and toppings, making it more visually appealing and easier to work with.