Cook spaghetti in salted, boiling water until al dente, according to the package directions. Reserve ½ cups of pasta cooking water before draining the pasta.
Rinse the mushrooms under runny, cold water to remove dirt or debris, pat dry with paper towels, slice them and set aside.
Heat the olive oil in a large skillet over medium heat. Add garlic and chilli flakes and cook gently for about 1 minute until slightly golden and fragrant.
Add the mushrooms to the skillet and season with salt and pepper. Cook, stirring and tossing frequently until the mushrooms are sizzling and brown, about 7 minutes.
When the spaghetti is done and al dente, drain it and add it to the skillet along with the parsley, grated parmesan cheese, and some of the reserved cooking water. Toss over medium heat for 1 minute, until everything is combined nicely.
Serve immediately, sprinkled with extra grated parmesan and chilli flakes if desired. Enjoy!
Notes
The nutrition values are for one serving and are based on an online nutrition calculator. They are estimates only.