Cook the fettuccine in salted boiling water according to package directions until al dente, then drain and set aside.
Season the chicken breast with black pepper, then heat olive oil in a large skillet over medium-high heat and sear the chicken for 5 to 6 minutes per side until golden and cooked to 165°F / 74°C, then slice and set aside.
In the same skillet over medium heat, melt the butter and sauté the garlic for 30 seconds until fragrant.
Pour in the heavy cream and bring to a gentle simmer for 3 to 4 minutes, stirring occasionally, until slightly thickened.
Remove from heat and whisk in the parmesan cheese until smooth and creamy.
Add the cooked fettuccine to the sauce and toss until evenly coated, then top with sliced chicken and serve immediately.