Prepare the Milano shortcrust pastry: put the slightly softened butter into small pieces in a bowl, the honey and the sugar and start working, then add the yolk and the salt well dissolved in the water, then the vanilla and finally also the flour and peel of lemon.
Work briefly on the work surface, then line with cling film and let it rest in the fridge for at least 2 hours (or even overnight).
Take the dough, roll it out on a lightly floured surface and create your cookies with the molds you have chosen (mine were about 8 cm): remember that the cookies will be coupled 2 to 2, so each mold must be used a number equal of times (for example, to prepare 20 cookies with 4 different molds I used each mold 10 times, creating 5 whole cookies with each shape).
With a different mold, go to pierce half of your biscuits (again because the biscuits must be combined like bull's eyes, so the top layer must be pierced to reveal the filling), then place your biscuits on the tray lined with paper oven, slightly separated from each other.
Bake in a preheated convection oven at 180 ° C for about 10-12 minutes or until lightly browned, then remove from the oven and let cool completely.
Once cold, start filling the biscuits: arrange all the bases (biscuits without holes) on the work surface and spread them with a light layer of Nutella.
Separately, arrange all the covers (the perforated biscuits) and sprinkle them with icing sugar.
Finally, cover each base with the respective cover, then decorate with a sprig of Nutella (with the help of a sac-à-poche with a star-shaped spout) and a little chopped hazelnuts.
The Christmas bull's-eye cookies are ready, you just have to serve them.