Prepare all the ingredients.

Mince the onions.

Sweat them without browning in stewpan along with olive oil.

Add the pumpkin cut in large dice...

...and add 2 dl water gradually.

Add salt and pepper.

Cook covered on low heat for about 20 minutes.

Meanwhile, scrape the mussel shells.

Place them in a stew pan...

...with white wine.

Cook covered for a few minutes...

...until they open. Drain them and keep their cooking juice.

Shell the mussels (keep a few shell on).

Once cooked, purée the pumpkin.

Add the juice of the mussels...

...the crème fraîche and pastis.

Dress and serve hot.