Wash the potatoes well; peeling is not necessary. Make cuts with an accordion without cutting to the end.
Cut the sausage into plates, and grate the cheese on a coarse grater.
Lubricate the potatoes between the cuts with oil, salt on top to taste and bake at 180 degrees for 40-50 minutes, depending on size.
Then insert the sausage into the cuts and grease with ketchup.
Sprinkle with grated cheese and put in the oven for 10 minutes. Sprinkle with chopped herbs before serving.