In a large pot of salted boiling water, cook the pasta until al dente. Reserve ½ cup of cooking water, drain and reserve.
While the pasta is cooking, heat a large skillet over medium-high heat and add the butter and olive oil. Once melted, add the sliced mushrooms and cook them until most of the liquid has evaporated.
Add the minced garlic, chopped parsley, and red pepper flakes.
Pour in the white wine and simmer until reduced by half.
Mix in the chicken stock, heavy cream, and grated parmesan cheese. Cook until the sauce has thickened.
Stir in the cooked fettuccine pasta, and cook until heated through. If you feel the sauce is too thick, add a little of the reserved pasta cooking water. Serve hot with additional grated Parmesan cheese and chopped parsley on top.