Stir the butter in a slow speed mixer. Add the egg yolks one by one. While stirring, mix in a bowl the flour, sugar, baking soda and a pinch of salt. And add them to the whipped butter. When the dough is ready, shape two balls, but without them interfering long not to become tough, and leave them in the fridge. Thus prepared, the dough can stand for months in the freezer. Once the balls are tight for a few hours in the refrigerator, grated grater one in a baking dish. Top spread raspberry (or another of your choice) sweet. Grate and second ball in a separate bowl and with that part of the dough sweet cover. Bake about 40 minutes in a preheated 180 C oven. Even before cool, sprinkle the finished malt with a thick layer of powdered sugar.