Combine sugar and honey in a saucepan and heat over low heat, so that they melt, but without coming to a boil.
Put the flour and baking soda in a bowl, add the egg first, then the slightly softened butter, then the mandarin with the spices and finally the mixture of honey and sugar.
Wrap the dough with cling film and let it rest in the fridge for at least 3 hours.
Take the dough, roll it out on a lightly floured surface with a thickness of about 3mm and first cut out a 13×20 cm rectangle and then some 3×3 cm squares. With the leftover pastry create cookies with the Christmas molds.
Brush with milk and cook at 180 ° C in a preheated convection oven: the rectangle for about 10-15 minutes …
… and the squares for 8 minutes, then let them cool down well.
Prepare the ice by mixing egg white and powdered sugar and decorate your biscuits as you like, numbering them from 1 to 24 and then attaching them to the rectangle with a little bit of ice (so that to eat each biscuit you will have to remove it from the rectangle), then let it dry .
The cookie Advent calendar is ready, you just have to enjoy it.