Bring a large pot of salted water to a boil and cook the fettuccine until al dente. Reserve 1/2 cup of pasta water, then drain.

In a large skillet over medium heat, melt the butter and sauté the garlic for about 1 minute.

Pour in the heavy cream and simmer for 3–4 minutes, stirring occasionally.

Reduce the heat to low, add the Parmesan cheese, and stir until the sauce is smooth.

Add the cooked fettuccine to the sauce, tossing until well coated. Add pasta water to thin if needed.

Season with salt and pepper. Garnish with fresh parsley if desired. Serve hot.