The hearts are washed well with cold water. Clean and cut them into small pieces. Cut the onions into rings and fry them in some of the butter until transparent. The carrot is cut into small pieces and added to the onion.
Fry for 3-4 minutes over medium heat, stirring continuously. Add the hearts, salt and fry everything until soft. The garlic is cut into small pieces and added to the hearts.
Add the remaining butter and some hot water, top with a lid and stew for 20 minutes on low heat. Add chopped parsley and after two minutes remove the dish from the heat.