Preheat the oven to 400°F (200°C). Slice the top from the garlic head to expose the cloves. Drizzle with a little olive oil, wrap loosely in foil, and roast for 35–40 minutes, or until the cloves are soft and golden. Let cool slightly, then squeeze the roasted cloves from their skins and mash into a smooth paste.
Bring a large pot of generously salted water to a boil. Cook the fettuccine according to the package directions until al dente. Before draining, reserve about ½ cup of the pasta water.
Pat the chicken breasts dry and season both sides with Italian seasoning, garlic powder, paprika, ½ teaspoon salt, and black pepper.
Heat 1 tablespoon olive oil in a large skillet over medium heat. Add the chicken and cook for about 5–7 minutes per side, depending on thickness, until golden and cooked through to an internal temperature of 165°F (74°C).
Transfer the chicken to a plate and let it rest for 5 minutes before slicing into strips.
Reduce the skillet heat to medium-low and add the butter. Once melted, stir in the mashed roasted garlic and cook for about 30 seconds.
Pour in the heavy cream and stir until smooth. Let it gently simmer for 2–3 minutes, but avoid a rapid boil.
Reduce the heat to low and gradually stir in the freshly grated Parmesan until melted and smooth. Season with the remaining salt as needed.
Add the drained fettuccine to the skillet and toss until evenly coated. If the sauce is too thick, add reserved pasta water a tablespoon at a time until it reaches your preferred consistency.
Arrange the sliced chicken over the creamy fettuccine. Garnish with fresh parsley and additional Parmesan, if desired, and serve immediately.