Bring a large pot of generously salted water to a boil. Cook the fettuccine pasta according to the package instructions until al dente. Drain, reserving half a cup of the starchy pasta water, and set aside.
Season the chicken breasts evenly with salt and black pepper. Heat the olive oil in a large skillet over medium-high heat. Sear the chicken for 5-7 minutes per side until deeply golden brown and cooked through (165°F internally). Remove from the skillet, let rest for 5 minutes, then slice.
In the same skillet, reduce the heat to medium-low and melt the butter. Add the minced garlic and sauté for 1 minute until highly fragrant.
Stir in the heavy cream and simmer gently for 2 to 3 minutes to allow the sauce to slightly thicken. Remove the skillet completely from the heat.
Whisk in the freshly grated Parmesan cheese and black pepper until the cheese is completely melted and the sauce is perfectly smooth.
Add the cooked fettuccine to the warm sauce, tossing gently to coat the noodles. If the sauce appears too thick, splash in a little reserved pasta water until you reach the desired consistency.
Top the creamy pasta with the sliced pan-seared chicken, garnish with fresh chopped parsley, and serve immediately.