Clean the chicken livers and wash them well and drain them. Heat some water in a suitable container and put the livers to be cooked until you get almost done with the crushed bay leaf and wait for the water to boil off completely.
Then add the butter and mix. Allow to sauté for 10 minutes or until completely done. Finally, add the spices and mix the mustard in. Serve the livers in butter with freshly chopped parsley.