Bring a large pot of salted water to a boil and add the spaghetti or fettuccine, cooking until al dente, about 8-10 minutes. Drain, reserving 1 cup of the starchy water.

Season the chicken breasts with salt and pepper. Heat olive oil in a skillet and cook the chicken for 6-7 minutes on each side until golden brown. Let rest and slice.

Cook thick-cut bacon in the same skillet until crispy, about 4-5 minutes. Stir in minced garlic and sauté for 30 seconds.

Lower the heat, pour in the heavy cream, and whisk while adding Parmesan cheese until smooth, about 2-3 minutes. Adjust thickness with reserved pasta water as needed.

Combine sliced chicken and drained pasta with the sauce and toss together, adding reserved pasta water for desired creaminess.

Plate the dish, garnish with parsley and extra Parmesan if desired, and serve hot.