Prepare all the necessary ingredients. The butter should be frozen, from the freezer.
For the filling, dry the walnuts in the oven, cool and grind in the bowl of a blender into crumbs.
In a bowl, sift high-quality flour, mix with a whisk with a pinch of salt and vanilla.
In the flour mixture, grate the frozen butter on a large grater, constantly dipping the butter in flour, rub it with your hands into small crumbs.
To the butter-flour mixture, add sour cream, egg yolks, lemon zest, knead the dough.
Collect the dough into a ball, tighten with cling film and put it in the refrigerator for an hour.
Whisk the whites with a mixer into a foam, add powdered sugar, beat until peaks.
Add ground walnuts to the whites and mix gently. The filling is ready.
Take the dough out of the refrigerator, cut off half, put the second part back in the refrigerator. Roll out the dough into a layer 3 mm thick, cut out circles with a diameter of 6 cm.
In the center, put the nut filling, pinch in the form of a dumpling
Place on a baking sheet, seam down.
Repeat the same with the remaining dough.
Bake in a well-preheated 180*C oven for about 20 minutes, do not over-dry, the cookies should not be browned. Consider the features of your oven.
Ready cookies to cool a little and warm roll in powdered sugar.
You don't even need to invite anyone to the ready-made cookies, everyone pulls themselves up.