Christmas Bûche de Noël (Yule Log)

The bûche de Noël — the Christmas Yule Log — is one of France's great seasonal confections: a rolled sponge cake filled with buttercream or ganache, iced to resemble a log, and decorated with seasonal garnishes (meringue mushrooms, marzipan holly, powdered sugar 'snow'). The preparation requires two technical skills in sequence: making a genoise or biscuit roulé (a flexible sheet sponge that can be rolled without cracking) and making the filling and exterior icing (typically chocolate ganache or coffee buttercream). The rolling technique is specific — the sponge must be rolled while warm into a clean tea towel to 'train' its curl, then unrolled, filled, and re-rolled once cool. A sponge that cracks on rerolling is the most common failure, typically caused by over-baking or rolling when fully cold.