Slightly soften the cold butter from the fridge, but it should still be cold.
Put the flour, egg yolks, and whole egg into the machine, add the sugar, lemon zest, the butter cut into medium-large pieces, and any flavorings (cinnamon, vanillin, etc.).
Knead at low speed for about 1 minute, then increase the speed to maximum for a few minutes (max 3 minutes).
The dough should not form a string, so it will be slightly crumbly. During kneading, if the dough sticks to the walls, use a spatula to detach it and bring it back to the center.
Remove the dough and finish smoothing it by hand on the work surface, shape it into a log, and cover it with plastic wrap. Let it rest in the fridge for 30/30 minutes.
