Mailänderli are the most popular and most frequently baked Christmas biscuit in Switzerland. In Austria, of course, we know it too and here it is simply called a “biscuit”, whereas in Germany they speak of “biscuits”. The only difference with the latter two is that with the Mailänderli, a little lemon zest is incorporated, which gives the pastry a wonderfully fresh note that was previously unknown to me.
Why the pastry is called “Mailänderli” and what exactly the connection to Milan is, no one can say with absolute certainty. However, researchers assume that a Swiss legation introduced them to the court of the Duke of Milan, the biscuits came to Florence in a roundabout way and were “discovered” there by Catherine de Medici and called “Mailänderli” after their origin. Whereupon the name became generally accepted and came back to Switzerland in a roundabout way.
In any case, they have been among the classics of Swiss Christmas baking since the 18th century and we find them in numerous cookery books of the time as “Gâteau de Milan” (“Cake from Milan”), “Miläänli” or even “Myyläänli”. It also seemed to have been the custom to offer guests some spiced wine and Miländerli on New Year’s Day.
In the winter of 2014/2015, a small “Christmas miracle” happened – while clearing out an attic, an old booklet was found that had stood the test of time here. The finder handed it over to the historian Walter Letsch, who was thrilled by it, as it seemed to be a collection of recipes from the time between 1559 and the beginning of the 17th century. Leafing through the recipes, the author must have hardly believed his eyes, because he also found, more than 100 years earlier than assumed, a recipe for the “Meilandische Biscotini”: “Take the yolks of 12 fresh eggs, ½ pound each of flour and sugar, mix the eggs and sugar for half an hour, then stir in the flour as well and shape it according to the rules of art.” 
 News from Mailänderli, Leckerli & Co.”, online source: Panissimo 6 December 2019