Peel the potatoes and cut them into pieces. Boil them until tender. Sieve and smash them with a fork.
Meanwhile, heat the oil and add the carrot and the onion. Cook until gold then add the minced seitan and cook for two more minutes.
Beat the egg. Add to the smashed potatoes the beaten egg, the milk, cream and 30g of Gruyère.
In a oven pan delay the minced seitan than add a layer of smashed potatoes.
Cover with grated Gruyère and put in a preheated oven for ten minutes to brown the cheese.