Work the eggs and the flour to a stiff dough, and let stand for 30 minutes. Divide the dough in two or three pieces, then roll out very thinly on a floured board, and let the paste dry for about 1 hour. Next roll into a long thin roll, and cut into long strips about a quarter of an inch thick. Boil in salted water for 3 or 4 minutes, put on a sieve and pour cold water over them. Drain thoroughly, and put a layer of noodles in a fireproof dish and pour the following sauce over them: Put the sour cream in a saucepan over a very slow fire, mix in the yolks of egg, the chopped ham and a little Gruyère cheese, finely grated, and season with salt and pepper. Pour some of this sauce over the layer of noodles, cover with another layer of noodles, and sauce, sprinkle with grated cheese, breadcrumbs, dot with pats of butter and put in a moderate oven to brown for 35 minutes.