Icing Sugar Dusting for Crispness

Dusting choux pastry with icing sugar (powdered sugar) before baking is essential for achieving the classic crisp shell that makes eclairs special. The sugar creates a barrier that helps the pastry develop its characteristic texture and prevents it from becoming soft. 

In The Great British Bake Off Season 14, when Dan forgot this step, he immediately knew his eclairs wouldn't be as hollow or crisp as desired. The icing sugar also contributes to the golden color and helps create those beautiful air pockets inside that are perfect for filling with cream.