Boil salted water in a large pot
Add spaghetti and cook until al dente
Reserve some pasta water
Slice garlic thinly
Heat olive oil in a pan over low heat
Add garlic and cook until lightly golden
Add red pepper flakes
Add cooked spaghetti to the pan
Toss well to coat the pasta
Add reserved pasta water as needed
Season with salt and black pepper
Add chopped parsley
Serve immediately