Cook the fettuccine according to the package instructions. Drain and set aside, reserving a bit of pasta water for later if needed.
Heat olive oil in a large skillet over medium-high heat. Season the chicken cutlets with salt, pepper, and garlic powder. Cook the chicken for 4-5 minutes per side, until golden and cooked through. Remove the chicken from the skillet and set aside.
In the same skillet, add the mushrooms and cook for 3-4 minutes, until they’re tender. Pour in the Marsala wine and chicken broth, stirring to combine. Let the sauce simmer for 5 minutes, allowing it to reduce and thicken slightly.
Add the heavy cream and butter to the skillet, stirring until the sauce becomes smooth and creamy. Return the chicken to the skillet, then toss the cooked fettuccine into the sauce. Stir well to coat the pasta, and sprinkle with Parmesan cheese. Garnish with fresh parsley and serve immediately.