Preheat oven to 225 ° C.
Boil potatoes  for 15 minutes, then place them on an oiled baking sheet and bake for about 30 minutes. Then cool them for 30 minutes.
Halve potatoes lengthwise and hollow out. Mash potato mass with a fork. Add soft butter, finely chopped cheese, tuna, and the chopped herbs and mix well. Season with salt and pepper. Place the mixture into the potato halves and gratinate at 180 °C.