Cook spaghetti in salted boiling water according to package instructions until al dente. Reserve 1 cup of pasta water and drain the rest.

While the pasta is cooking, heat olive oil in a large pan over medium heat. Add garlic and red pepper flakes, sauté until garlic is golden and fragrant.

Add the cooked spaghetti to the pan, tossing to coat with the garlic oil. Add a bit of reserved pasta water if needed for moisture.

Mix in the chopped parsley and half of the Parmesan cheese.

Serve immediately, topped with remaining Parmesan cheese.