Bring a large pot of water to a boil and cook the fettuccine just before al dente according to package instructions. Drain and keep aside with 1 cup of the pasta water reserved in case the sauce becomes too thick.
While the pasta is cooking, heat olive oil in a large skillet over medium heat. In a shallow dish, combine flour, salt, and black pepper. Dredge each chicken breast lightly in the flour mixture and shake off any excess flour.
Once the oil is hot, add the coated chicken breasts to the skillet. Cook them for about 5 minutes on each side until nicely browned and fully cooked through. Remove the chicken and set aside.
To prepare the sauce, use the now-empty pot. Melt the butter over medium heat and add the minced garlic and garlic powder, cooking just until the garlic becomes aromatic, about 30 seconds.
Stir in the flour, mixing well until fully combined and no dry bits remain. Gradually whisk in the chicken stock, white wine, and heavy cream, then mix in the red pepper flakes, dried parsley, and salt.
Let the sauce gently simmer over medium-low heat for 10 minutes, stirring often to keep it smooth and flavorful.
Add the Parmesan cheese, stirring until it has melted completely into the sauce.
Incorporate the spinach, red pepper strips, and the roasted garlic cloves peeled from their skins. Stir the mixture until the spinach is just beginning to soften, roughly 2 minutes. Adjust seasoning to your taste.
Combine the cooked pasta into the sauce, stirring well to coat all the noodles evenly.
Serve the creamy pasta topped with the cooked chicken breasts immediately for a delicious dinner.
