1 medium Idaho potato, peeled
3 oz grated parmesan
1/2 tsp kosher salt
freshly ground black pepper
1/2 cup flour, or more as needed
1 ounce dried porcini mushrooms
1/2 cup liquid from rehydrating the porcini (see above)
2 tbsp butter
1 small red onion, sliced
1 tbsp minced garlic
2 oz shiitake mushrooms (can be dried and rehydrated) - separate caps from stems and slice the caps (but keep both)
handful of parsley stems
1 tbsp chopped parsley
1/2 cup dry white wine
1 cup heavy cream
1 oz prosciutto - doesn't have to be top quality, as it will be cooked
1/2 cup greens (we used arugula, but spinach or swiss chard might be more appropriate)
2 tbsp grated parmesan
First, make the gnocchi. Pour boiling water over the porcini and let them rehydrate for 15 minutes. Cook the potato in boiling salted water until tender. Mash it (or put it through a ricer, I just don't have one). Put in the refrigerator to cool, about 15 minutes. Drain your porcini, being careful to reserve 1/2 cup broth, stick on a food processor and blend until smooth.
Remove your potato from the fridge, dump it onto a clean work surface, form into a little volcano shape. Sacrifice the porcini paste, parmesan, egg, salt and pepper to Cthulu by throwing them into your volcano. Then destroy your volcano with your hands and mix it all up. Then add the flour and knead into a dough, using more flour if needed (I think I ended up using almost double the original amount). Divide the dough into quarters, wrap each in saran wrap. Clean the work surface. Take one of the quarters, roll it into a tube about as thick into your finger, and then cut into gnocchi side pieces. Indent each piece with a fork if you're feeling fancy; I quickly tired of this process and just made them into pillow shapes. Lay them out on a cookie sheet and set aside.
Start boiling water for your gnocchi. It is helpful to have two people at work here - in this case, I was on gnocchi duty, and Better Half made sauce. If you're doing it yourself, I guess you should probably do gnocchi first, because they'll re-heat in the sauce). When your salted water is boiling, add the gnocchi in batches. When they float to the surface, remove them with some kind of implement and drain.
Now, the sauce.
Melt 1 tbsp butter in a large pan and saute onions, mushrooms, garlic, parsley stems and shiitake stems. Cook until soft but not brown, approx 4 minutes. Add wine and porcini liquid. Bring to a boil then simmer until reduced to about 1/3. Add cream, reduce again "until the sauce coats the back of a spoon". This part, we had a hard time with, because it didn't seem to reduce. The recipe says you then strain it into a bowl and set aside. I dunno that you need to strain it, because everything in it is delicious.
Anyhow, in your newly empty saucepan, heat remaining butter (1 tbsp) until it begins to brown and add the chopped shiitake mushrooms caps. Saute 2-3 minutes. Return cream sauce to pan, along with prosciutto, greens, and half the parmesan. Cook 3-4 minutes. Season with salt and pepper. Add gnocchi to your cream sauce. Add remaining parmesan and parsley.