In a large pot or deep skillet, heat the olive oil over medium-high heat. Add the diced chicken and cook until browned on all sides, about 5-7 minutes.
Reduce the heat to medium and add the minced garlic, stirring for about 1 minute until fragrant.
Pour in the chicken broth and bring to a simmer.
Add the fettuccine to the pot, ensuring it's submerged in the broth. Cover and cook for about 10-12 minutes, or until the pasta is al dente, stirring occasionally.
Once the pasta is cooked, reduce the heat to low. Stir in the heavy cream, Parmesan cheese, salt, pepper, and nutmeg, mixing until the cheese is melted and the sauce is creamy.
If using, toss in the fresh spinach and allow it to wilt for about 2-3 minutes.
Taste and adjust the seasoning if necessary.
Remove from heat and let sit for a minute to thicken slightly before serving.
Notes
Serve in shallow bowls, drizzling a bit more cream sauce over the top and garnishing with fresh parsley for a pop of color.