Mix the ingredients for the shortcrust pastry roughly with a hand mixer (dough hook). Next, knead the dough with your hands to a uniform amount, form it into a ball and place it in the refrigerator for about 15 minutes.
Meanwhile, for the filling, separate the egg whites and egg yolks. Then mix the ground sugar, hazelnuts, apricot jam, the egg whites, half the egg yolks and bitter almond flavoring. Add the water gradually until the mixture is spreadable.
Spread out the work surface with cling film (it is best to work with two pieces of cling film so that the work surface is larger, the width of only one piece is too small). Place the dough ball on it and press it a little bit flat. Place a new piece of plastic wrap on top and roll out the dough into a rectangle of about 45×35 cm. Remove the top sheet and spread the filling evenly on the dough. Spread pine nuts and chopped walnuts evenly over the top.
Then roll up the dough carefully and tightly with the foil to form a long sausage (be careful not to roll up the foil!). Pinch the ends so that the filling does not fall out.
Grease the baking tray, place it next to the dough roll and lift the roll onto the baking tray. Fold the ends of the dough sausage over a little bit in a u-shape. Stir the remaining egg yolk with the milk and brush the nut wreath with it on all sides. Bake for about 45 minutes in a hot-air oven at 150-160 degrees. (Be