Peel potatoes and boil in salted water until al dente. Cool down them and halve lengthwise. Preheat oven to grill position.
Mix cheese with flour, egg yolks, milk, marjoram, crushed garlic, salt and pepper.
Cover potato- halves with the mixture, place upon a baking paper-lined baking sheet and gratinate in oven about 2 minutes until golden brown.