Cook the Pasta:
Bring a large pot of salted water to a boil. Add the fettuccine and cook according to package directions until al dente. Reserve ½ cup of pasta water, then drain and set aside.
Cook the Chicken:
Pat chicken dry and season both sides with salt, pepper, and garlic powder.
Heat olive oil in a large skillet over medium heat. Sear chicken breasts for 5–7 minutes per side until golden brown and cooked through (internal temp 165°F). Remove from skillet and let rest, then slice thinly.
Make the Alfredo Sauce:
In the same skillet, melt the butter over medium heat. Add minced garlic and cook until fragrant (about 30 seconds).
Pour in the heavy cream, stirring constantly. Bring to a gentle simmer, then lower the heat and whisk in Parmesan cheese until melted and smooth. Add a pinch of nutmeg, and season with salt and black pepper to taste.
Combine Everything:
Add the cooked fettuccine to the skillet and toss gently in the sauce until fully coated. If needed, add a splash of reserved pasta water to loosen the sauce.