Biscotti Noisette

The dough is soft because of the oil and yogurt, so it tears easily if the shell gets too thin - press the indentation deep but keep the walls even, then seal the seam completely and roll the ball smooth again. Always place the cookie seam-side down on the tray so gravity works with the seal, not against it. The 15-20 minutes of chilling before baking matters here too: cold dough holds its shape instead of spreading and splitting.

Yes, the filling already offers ground almonds or chopped hazelnuts as alternatives, so an all-hazelnut version works and gives a more intense noisette flavour. Chopped hazelnuts make the filling coarser than ground almonds, so you may need the second tablespoon of milk to get it moldable. Keep the total at 90 g either way so the 22 filling balls stay the right size for the dough.

Let them cool completely before storing - the filling stays warm and moist longer than the shell, and packing them early creates steam that softens the crust. Keep them in an airtight tin at room temperature; the high fat content from butter, oil and nuts keeps them tender for several days. Don't refrigerate them, as the cold dries out the nut filling.

Yes - you can mix the dough and the filling in advance and keep them covered in the fridge, then let the dough sit at room temperature until it is pliable enough to shape without cracking. You can also shape all 22 cookies, place them on the tray and chill them longer than the 15-20 minutes stated; a longer rest only helps them hold their shape. Brush with egg white and add the sliced hazelnuts just before baking so the topping stays neat.

The biggest one is adding all the flour at once - the recipe says to work in the ground hazelnuts, baking powder and flour little by little, because too much flour makes the dough dry and it cracks around the filling. The second is baking by colour on top: the tops are meant to stay relatively light, so check underneath and around the edges for golden colour instead of waiting for the surface to brown. Finally, unequal portions bake unevenly, so weigh the pieces at about 30 g each rather than dividing by eye.