Cook fettuccine in salted water according to package directions. Before draining, reserve ½ cup of the pasta water, then drain.

Melt butter in a large skillet over medium heat. Add garlic and cook for 1 minute, until fragrant.

Add cream cheese and stir until completely melted and smooth. Pour in heavy cream, bring to a gentle simmer, and cook 3 to 4 minutes, stirring often, until slightly thickened.

Reduce heat to low. Stir in Parmesan, salt, pepper, and nutmeg. Continue stirring for about 2 minutes, until the sauce is glossy.

Add drained pasta to the skillet. Toss to coat, adding reserved pasta water a little at a time until the sauce reaches your preferred consistency. Serve right away with extra Parmesan.