For the shortbread cookies, crumble butter and lard with flour, then knead in powdered sugar and yolks. Wrap your dough in cling film and chill for at least 2 hours.
Dust a pasta board with flour, roll out the dough and cut out the cookies with a cookie cutter. Line a baking tray with baking paper, place the cookies on it and bake in a preheated oven at 190 °C for about 10 minutes until golden brown.
Let the shortbread cookies cool down, spread with jam and glue two identical cookie pieces together and sprinkle with powdered sugar.