Bring a large pot of salted water to a boil. Add the fettuccine pasta and cook according to package instructions until al dente. Drain and set aside.

In a skillet over medium heat, melt 2 tablespoons of butter. Add the minced garlic and sauté for 1-2 minutes until fragrant.

Pour in the heavy cream and bring to a simmer. Reduce heat to low and stir in the grated parmesan cheese until melted and smooth.

Season with salt, black pepper, and red pepper flakes (if using).

Add the cooked pasta to the sauce and toss to coat evenly. If the sauce is too thick, add a little pasta water to reach desired consistency.

Remove from heat and stir in the remaining 2 tablespoons of butter until melted.

Serve hot, garnished with chopped parsley and additional parmesan cheese if desired.