Making a traditional BÃ»che de NoÃ«l is a lengthy project that requires time and planning. you'll want to make many of the components in advance so they have time to chill: the mushroom meringues, soaker, compote, and pastry cream keep for up to 2 days before use. Once you're ready to go, make the sponge for the cake just before assembly. It should cool but should not sit too long or it will dry out and crack. This cake features a flavor combination that I learned from a French baker who told me her mother made it this way when she was a girl. The combination of chestnuts, cranberries, and praline is unique, and transports her back to her childhood. The recipe for the chestnut pastry cream is adapted from Johnny Iuzzini's recipe, which appeared originally on the Martha Stewart Show.