I think that the flavours of spinach and mushrooms work well together, so long as you have something to temper the oxalic acid taste of the spinach. Cream or crème fraiche works well in that regard.
This is one of those easy supper dishes that is quick, filling and satisfying.
All I do is sauté a diced onion with some crushed garlic in olive oil and a little butter and then add some sliced chestnut mushrooms (wild ones such as girolles or ceps would be even better if you had some) and cook these with some salt and pepper while the pasta is cooking.
I like farfalle here, the shape just seems right, but I suppose any shape will work, although I think spaghetti would be wrong.
Once the pasta is done, I add it to the mushrooms and mix in with some washed baby spinach and grate in a bit of nutmeg.
As the spinach wilts, I add in a small tub of single cream or crème fraiche and cook everything until the spinach is done.
That is pretty much it, apart from a generous grating of fresh Parmesan and more black pepper.