Put the beans and 1 litre of water in a pot and bring to the boil. Cook over low to medium heat for about 1 3/4 hours. In the meantime peel and chop the onion. Clean, wash and slice the celery. Finely dice 2 slices and set aside. Coarsely dice the remaining celery
Finely dice the bread. Drain 25 g butter in a pan, add finely diced celery and roast for 6-8 minutes while turning. Add bread cubes and roast for another 4-5 minutes. Season with salt, remove from the pan
For the pesto, wash parsley and shake dry. Cut off the lower part of the stems. Cut the rest of the parsley roughly. Peel garlic and chop roughly. Put parsley, garlic and lemon juice in a small cup. Add cumin, salt and chilli powder. Puree with a blender, letting the oil run in
Melt 25 g butter in a pot, fry onions and coarsely diced celery in it while turning, add cooked beans with liquid (only very little is left). Season with salt and pepper. Deglaze with stock and cream. Bring to the boil and cook for 15-20 minutes. Remove from the heat and puree finely with a blender. Season again with salt and pepper. Serve the soup in deep plates. Sprinkle with croutons and sprinkle with pesto