8-10 oz. penne pasta
3 cups medium mushrooms (shitake or porcini), stems removed, sliced
3 cups spinach
1 cup heavy cream
3/4 cup Parmesan cheese
1/2 cup walnuts, roughly chopped
1 tablespoon freshly squeezed lemon juice
1 tablespoon extra-virgin olive oil
kosher salt and freshly ground pepper, to taste
Bring a large pot of generously salted water to boil.
Heat 1 tablespoon olive oil in a large pan or skillet over medium heat and saute mushrooms, seasoned with salt and covered, for 15-20 minutes, or until softened.
Stir occasionally and reduce heat if mushrooms start to burn.
Add spinach to mushrooms and pour in lemon juice. Cook until wilted, then add walnuts.
Cook pasta according to packaging directions, or until al dente. Drain (reserving 1/2 cup pasta water) and set aside.
Add heavy cream to the spinach and mushrooms, stirring well, and mix in Parmesan cheese. If sauce is too thick, add pasta water one tablespoon at a time.
Taste and season with salt and pepper, if necessary.
Pour drained pasta into the sauce and toss well to coat thoroughly. Cook on low heat for 5 minutes, or until sauce thickens and sticks to pasta.
Transfer to serving plates, garnish with more Parmesan and serve hot.