Pass the chestnuts and potato through the mouli-légume whilst still warm. Add the flour, egg yolk and salt to the chestnut and potato mixture. Knead all the ingredients together. Continue as for potato gnocchi.
Boil the gnocchi in plenty of salted water. When they rise to the top of the water, drain them. Toss the gnocchi in melted butter and sprinkle with Parmesan. Serve with pheasant or any other game cooked with a sauce.