Heat large pot of water to boiling over high heat. Add farfalle and large pinch of salt and cook pasta according to package instructions for al dente. Reserve 1/2 cup pasta cooking water, then drain pasta and set aside.

Meanwhile, while pasta water is coming to a boil and pasta is cooking, heat olive oil and butter in large Dutch oven over medium heat. Add mushrooms and cook 12 to 14 minutes or until mushrooms are deep golden brown and most liquid has evaporated, stirring frequently. 

Add garlic, 1/2 teaspoon salt, black pepper and red pepper flakes to mushrooms, and cook 1 minute, stirring constantly. 

Add cream, wine and lemon zest to mushroom mixture. Heat to boiling over medium-high heat, then reduce heat to medium and cook 5 to 6 minutes or until mixture is thickened to a thin sauce consistency, stirring frequently. Reduce heat to low.

Add spinach, Parmesan cheese and remaining 1/2 teaspoon salt to sauce mixture. 

Add pasta and 1/4 cup pasta cooking water on top of spinach. Cook over low heat 1 to 2 minutes, tossing frequently, or until spinach is just wilted. If sauce is too thick, add additional cooking water a tablespoon at a time until desired consistency is reached.

Serve garnished with parsley and additional Parmesan cheese, and lemon wedges for squeezing over pasta, if desired.