In a large pot, bring salted water to a rolling boil. Add the fettuccine pasta and cook according to package instructions until al dente. Once done, drain the pasta, reserving 1/2 cup of the pasta water for later. Set the drained pasta aside.
While the pasta cooks, season both sides of the chicken breasts with salt, pepper, and Italian seasoning. In a large skillet, heat the olive oil over medium heat. Once hot, add the chicken breasts to the skillet. Cook for about 6-7 minutes per side until the chicken is golden brown and cooked through. Use a meat thermometer to ensure the internal temperature reaches 165°F (75°C). After cooking, remove the chicken from the skillet and allow it to rest for a few minutes before slicing it into bite-sized pieces.
In the same skillet used for the chicken, add the minced garlic. Sauté for approximately 30 seconds, just until the garlic becomes fragrant. Next, add the fresh spinach and cook, stirring frequently, until the spinach has completely wilted.
Lower the heat to a gentle simmer. Pour the heavy cream into the skillet, stirring to combine with the garlic and spinach. Gradually whisk in the grated Parmesan cheese, continuing to stir until the cheese is fully melted and the sauce is silky smooth. If you find the sauce is too thick, add small amounts of the reserved pasta water until you achieve your desired consistency.
Add the cooked fettuccine and the sliced chicken into the skillet. Gently toss everything together, ensuring the pasta and chicken are well-coated in the creamy sauce. Taste the dish and adjust seasoning with additional salt and pepper as needed.
Plate your delicious Cheesy Garlic Parmesan Chicken Pasta while it's hot. Garnish with fresh chopped parsley for an extra pop of color and flavor.