For the muesli crackers, put spelt flour, wheat flour and oat flakes in a bowl. Add about a third of the milk and let it swell for about 50 minutes. Then crumble in the yeast and add the remaining ingredients. Knead well to a smooth dough. Cover with a tea towel and let rise for 45 minutes. Shape the dough into rolls with wet hands and place them on a greased baking tray, spacing them apart. Let rise for another 20 minutes. Prick each roll several times with a fork and bake in a preheated oven at 200 °C for 20-25 minutes.