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.
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.
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.