Peel and pit the chayotes, cut them into slices, put them in a saucepan and cook them in salted boiling water (very lightly) for about 10 minutes. Drain them well if you want to avoid water in the gratin.
Lightly grease a gratin dish, put them in this dish.
Peel, finely chop the shallot, spread over the chayotes.
Prepare a mixture with the cream and the whole egg, mix well.
Preheat the oven to 200°C.
Spread the Guérande salt and lightly crushed Sichuan pepper over the chayotes.
Then cover with grated cheese.
Put in the oven and cook until the surface is golden brown and crispy.
Serve immediately.
