Soak the morels in cold water for 1 hour.
For the dough, mix the flour, eggs and oil with 1 tsp salt to form a smooth, supple dough. Add extra cold water or flour, if necessary.
Shape the dough into a ball and leave wrapped in cling film for 30 minutes.
Divide the dough in half and roll out on a floured surface to about 1-2mm thick. Dust with flour, roll up and cut into 1cm wide strips. Allow to dry, spread out and covered, for 20 minutes.
Cook in boiling salted water for 3-4 minutes until al dente or tender with a little bite.
Tip the mushrooms into a sieve and collect the liquid, passing it through a fine cloth. Cut the morels in half.
Peel and finely chop the shallot.
Saute the shallot in a hot pan with the butter until translucent. Add the morels and cook briefly. Pour in the sherry and allow to bubble. Pour in the water and cream and simmer for a few minutes until creamy.
Mix the drained pasta with the sauce, season with salt and pepper and serve garnished with chervil.