Why is it important to bake cream puffs and éclairs thoroughly and cool them slowly?

Baking cream puffs and éclairs thoroughly is crucial because it ensures the proper expansion and structure of these delicate pastries. When the pastries are baked, the moisture present in the dough turns to steam, causing them to puff up and create a hollow center. If they are not baked thoroughly, the moisture can remain trapped inside, leading to a collapse once they are removed from the oven. Additionally, cooling them slowly in the turned-off oven helps to prevent rapid temperature changes that could cause the outer structure to crack or collapse. This gradual cooling process allows the steam to escape in a controlled manner, maintaining the integrity of the pastry. This attention to baking and cooling directly influences the final product's stability and overall success.