Bring a large pot of water to a boil and cook the fettuccine according to package instructions until just before al dente, then drain and keep aside with some pasta water reserved in case the sauce needs thinning.
While the pasta cooks, heat olive oil in a skillet over medium heat and season the flour with salt and pepper in a shallow dish.
Coat each chicken breast lightly with the seasoned flour, shaking off the excess, then brown the chicken for about 5 minutes on each side until fully cooked, then set aside.
In the same pot used for the pasta, melt the butter over medium heat and stir in the minced garlic and garlic powder, cooking until aromatic for around 30 seconds.
Whisk in the flour until it forms a smooth paste and then gradually add chicken stock, white wine, and heavy cream while stirring to blend.
Season the sauce with red pepper flakes, dried parsley, and salt, then reduce the heat and let it simmer gently for 10 minutes, stirring occasionally.
Stir in the Parmesan cheese until melted and then fold in the spinach, red peppers, and peeled roasted garlic cloves, allowing the spinach to wilt over about 2 minutes.
Combine the cooked pasta with the sauce, tossing well to coat, and adjust the consistency with reserved pasta water if needed.
Serve the creamy pasta immediately topped with the cooked chicken breasts for a satisfying and flavorful meal.
