for the gnocchi:
peel the potatoes and boil them in lightly salted water until tender (20-25 minutes).
peel and dice the squash. place in a bowl, cover and cook in the microwave for 8 minutes on full power.
press potatoes and squash through a ricer or mash until smooth. add the flour, egg yolks and seasoning and make a soft dough using your hands. add more flour if the mixture is too sticky.
prepare a clean dry surface and dust it with flour. roll the dough into sausages about 1.5 - 2cm thick. cut these into little squares. to shape the gnocchi roll the piece of dough over an upturned fork to create ridges on the one side and a hollow on the other where you press with your thumb (dip the fork in flour to prevent sticking). this will produce nice oval shaped gnocchi with ridges to hold the sauce. place the prepared gnocchi on a plate dusted with flour. arrange them carefully so that they don't touch.
bring a large sauce pan of salted water to boil and simmer the gnocchi in batches until they float to the surface (3 minutes or less). remove with a slotted spoon and place in a bowl with cold water. drain and toss with a little olive oil or melted butter. reheat before serving.
for the sauce:
cover the mushrooms with boiling water and leave to stand for 30 minutes.
heat the oil in a heavy based sauce pan and saute the onion until soft. add the mushrooms with the liquid. add black pepper and vegetable stock. cover and cook for 15-20 minutes. if the sauce becomes too dry, add a little water.
add the cream and cook for 5 minutes. stir in the parsley reserving a little for serving.
serve with a dash of lemon juice and grated parmesan.