Quickly mix all ingredients in a mixing bowl or on a work surface to form a shortcrust pastry. Let rest in refrigerator, covered with plastic wrap, for 2 to 3 hours before processing. Roll out on a floured work surface or between two baking mats. Sweep off excess flour with flour whisk or brush. Cut out any shapes you like. Place on prepared baking sheet. Brush with salted egg spread (about 4 g salt per egg) if desired and bake in preheated oven at 165 to 175 °C for 12 to 14 minutes until golden brown on sight.
Variation: You can also form the dough into oblong rolls and put them in the refrigerator until the rolls are firm to the touch. Dilute the egg yolk with a little water in a shallow container and turn the rolls well in it. Then roll in coarsely chopped nuts. Press the nuts or kernels down well. (Chopped sunflower seeds, pumpkin seeds, etc. are also suitable) Cut thin slices with a sharp (saw) knife and bake as described above.