Cut the pumpkin into cubes, steam until soft for about 20 minutes, puree, leave to cool. Put the flour, eggs, salt and pumpkin puree in a bowl and beat to a smooth dough, leave to rest for 30 minutes.
Finely chop the onion, cut the leek into rings. Sweat both together in hot oil, deglaze with cider. Add the stock and chestnuts, cook for 10 minutes, season with rosemary, salt and pepper.
Cut the Emmentaler AOP in small cubes. Heat a good amount of salted water. Push the dough through a button spaetzle sieve in portions directly into the simmering water. As soon as the button spaetzle rise to the surface of the water remove using a slotted spoon. Add the button spaetzle to the chestnut mix, heat briefly and mix in the cubes of cheese.