Mix 250 g flour, ammonium bicarbonate, 1 pinch of salt, sugar and vanilla sugar. Add lard and butter in flakes. Knead first with a hand mixer, then briefly with your hands until smooth
Cut the dough in half. Knead under 1 half cocoa. Form both doughs into a roll (approx. 25 cm), cut into slices of approx. 1 cm thickness, form into balls. Put them on trays lined with baking paper, press them a little flatter. Bake in the preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: level 2) for approx. 15 minutes