In a large skillet, heat the olive oil over medium-high heat. Add the chicken pieces, sprinkle with garlic powder, salt, and pepper, and cook until the chicken is browned and cooked through, about 5-7 minutes. Remove the chicken from the skillet and set aside.

In the same skillet, add the sliced mushrooms and cook for about 3-4 minutes until they are tender. Add the chopped spinach and cook for an additional 2 minutes until wilted.

While the vegetables are cooking, bring a large pot of salted water to a boil. Add the fettuccine and cook according to package instructions until al dente. Drain and set aside.

Reduce the heat to medium-low in the skillet with the mushrooms and spinach. Pour in the heavy cream and bring to a gentle simmer. Stir in the Parmesan cheese and Italian seasoning, mixing until the cheese is melted and the sauce is creamy.

Add the cooked chicken and drained fettuccine to the skillet. Toss everything together until the pasta is well coated with the sauce. Cook for an additional 2-3 minutes to heat through.

Serve immediately, garnished with fresh parsley.