For the nut puffs, knead a smooth shortcrust pastry from the dough ingredients. Depending on the consistency of the sour cream, the dough may need a little more flour or sour cream. Cover and let rest in the refrigerator for 30 minutes.
For the nut filling, mix nuts, sugar, egg whites, rum and milk until smooth. Allow to set so that the filling is easily moldable. If necessary, stir in a little more milk or nuts. Divide the dough into thirds.
Roll out the dough piece to about 15 cm wide. Pile one-third of the nut filling in a strand on the bottom center of the dough, fold the bottom dough over it and roll it up.
Using a floured wooden spoon handle, press off approx. 3 cm wide pieces from the dough roll and place on a baking tray lined with baking paper. Do the same with the other two pieces of dough.
Bake at 200 degrees top and bottom heat for about 25 minutes. While still hot, sprinkle with powdered sugar and vanilla sugar.