Butter a small, rimmed baking sheet or roasting pan (10X14) and dust it with flour. Run a knife around the edge of the baked cake and turn the pan upside down on the towel, leaving the pan on top of the cake until it is cool.
Pour the batter into the pan and smooth it evenly with a knife. Make the butter cream, using 5 egg yolks, and add to it the dissolved instant coffee.
That's when thinly rolled sponge cakes filled with jam or cream and covered with buttercream icing begin to show up in European cook books.
Fold in the flour and then the butter, which should be cooled.Fold in the beaten egg whites gently but thoroughly.A description of pulling sugar was written down about 1500 in the York manuscript, under the title To make penydes...The art of pulling sugar was evidently well understood 500 years ago..." ---Sugar-Plums and Sherbet: The Prehistory of Sweets, Laura mason [Prospect Books: Devon] 2004 (p.528)  "Buche de Noel Cuire des marrons, trois minutes; extraire leur chair de leur cosse. Rinse the mixing bowl with hot water and wrap a hot wet towel around the base.
Combine the egg yolks and sugar and beat for 5 minutes or until the mixture has doubled in volume.
Buche de Noel is one of many traditional cakes baked at Christmas. The name of this recipe literally translates as "Christmas log," referring to the traditional Yule log burned centuries past.
The ingedients suggest the cake is most likely a 19th century creation.
84-5) "When sugar first became known in Europe it was a rare and costly commodity, valued mainly for its supposed medicinal qualities and finding its place in the pharmacopoeia of the medieval apothecary...
Sugar gradually became more widely available in Europe during the Middle Ages.
Sprinkle very lightly with green sugar." ---The Complete Tante Marie's French Kitchen, Translated and adapted by Charlotte Turgeon [Oxford University Press: New York] 1962 (p. For other people, it was a special treat saved for holidays (Christmas, Easter) and other special occasions (weddings, christenings). This idea survives today in the form of cough drops.