In a large pot of boiling salted water, cook the spaghetti according to package instructions. Drain and set aside, reserving about 1/2 cup of pasta water.
While the spaghetti is cooking, season the chicken breasts with salt and pepper. In a large skillet, heat the olive oil over medium-high heat. Add the chicken and cook for 6-7 minutes on each side until cooked through and golden brown. Remove from the skillet and let it rest for a few minutes before slicing into strips.
In the same skillet (do not clean), reduce the heat to medium and add minced garlic. Sauté for about 30 seconds until fragrant, being careful not to burn. Add the heavy cream and bring to a gentle simmer.
Gradually stir in the grated Parmesan cheese, garlic powder, onion powder, and nutmeg. Keep stirring until the cheese is melted and the sauce is creamy. If the sauce is too thick, add some of the reserved pasta water to achieve your desired consistency.
Add the cooked spaghetti to the sauce, tossing it gently until well coated. Incorporate the sliced chicken into the spaghetti. Adjust seasoning with salt and pepper if necessary.
Plate the Chicken Alfredo Spaghetti into bowls and sprinkle with fresh parsley for garnish.
Notes
For a lighter version, use half-and-half instead of heavy cream.