Cook the spaghetti according to package instructions in a large pot of salted boiling water until al dente. Drain and reserve 1/2 cup of the pasta cooking water.

In a large skillet, melt the butter over medium heat. Add the minced garlic and red pepper flakes, cooking until the garlic is fragrant and lightly golden, about 2-3 minutes.

Add the cooked pasta to the skillet, tossing to coat in the garlic butter. If the pasta seems dry, add a bit of the reserved pasta water until the desired consistency is reached.

Stir in the grated Parmesan cheese and chopped parsley. Season with salt and black pepper to taste, mixing well to combine.

Serve immediately, garnished with extra Parmesan and parsley if desired.