Dissolve the yeast cubes in water, add sugar and mix. Mix the dissolved yeast with 150 g of wheat flour, let the pre-dough rise for 30 minutes.
Mix the spelled flour, buckwheat flour, the rest of the wheat flour and sunflower seeds and add to the pre-dough. Knead the dough well, shape into a ball, place on a baking sheet covered with baking paper and let rise for 30 minutes.
Meanwhile preheat the oven to 200 degrees Celsius.
Use a stick to make indentations in the dough, brush the surface with milk and place in the oven. The baking time is 30 minutes.