Prepare the langoustine soup in advance since it requires a homemade stock; after removing and crushing the heads and shells of the langoustines, chill the tail meat until ready to use. Prepare the stock as instructed and reserve.
Make the shortbread layer cake dough in advance; chill the dough for at least an hour before baking.
Leaf bread, a crisp flatbread decorated with intricate designs, is a holiday tradition in Iceland. Made of a thin, waferlike dough, it’s cut into geometric patterns, then deep-fried and saved to be eaten as an accompaniment to Christmas dinner. See our step-by-step guide to making it »