Bring a large pot of salted water to a boil and cook pasta according to package directions until al dente.
While pasta cooks, grate fresh Parmesan finely and set aside.
In a large skillet over medium-low heat, melt the butter gently to avoid browning.
Add minced garlic to the melted butter and sauté 30–45 seconds until fragrant.
Pour in the heavy cream, stirring to combine with butter and garlic.
Increase heat slightly and simmer the cream-butter mixture 3–5 minutes, stirring frequently.
Add a small pinch of nutmeg if using, then reduce heat to low.
Whisk in grated Parmesan gradually, allowing it to melt into a smooth sauce.
Season with salt and plenty of freshly ground black pepper to taste.
Drain pasta, reserving 1 cup pasta cooking water; add pasta to the sauce and toss.
If sauce is too thick, thin with reserved pasta water a tablespoon at a time until silky.
Finish with chopped parsley and an extra sprinkle of Parmesan before serving.