Bring a large pot of salted water to a boil, add the spaghetti and cook, until about three-quarters of the way done.
Meanwhile, heat the olive oil in a large saute pan over medium heat. Add the red pepper flakes and garlic and cook for about 2 minutes before adding the tomatoes and a pinch of salt and pepper. Cook until the tomatoes begin to blister, about 2-3 minutes. Add a ladle full of the pasta water and the chopped parsley to the tomatoes.
When the pasta is three-quarters of the way cooked (it will still have a good bite to it), remove it from the water and add it to the saute pan. The liquid will reduce as the pasta finishes to form a sauce.
Season with salt and garnish with fresh grated Parmesan cheese.
Since you are cooking the pasta separately, you can use any shape you'd like.