Heat oil: In a large sauté pan or medium saucepan, heat olive oil over medium-high until it's shimmering.
Add garlic and pepper flakes: Add garlic and the crushed red pepper flakes and sauté cook until the garlic is fragrant (no more than a minute, or it will brown).
Add tomatoes: Next, add in the tomatoes (also the juices). I break them up and remove the hard stem before I add them to the pan. Use your wooden spoon to break them up and stir.
Simmer the sauce: Once the sauce comes to a nice simmer, lower the heat to medium-low. Keep it simmering for about 25-30 minutes. Continue heating the sauce until it comes to a simmer. Then reduce heat to medium (or medium-low) to maintain a low simmer, and let the sauce cook for about 30 minutes, or until it reaches your desired consistency.
Boil pasta water: When you have about 15 minutes left of simmering, bring a large pot of water to boil. Add salt when it comes to a rolling boil.
Cook pasta: Add in the pasta, and cook until it's 1-2 minutes before al dente.
Stir in the parsley + salt : Then taste the sauce, and season with any extra salt, pepper and/or crushed red pepper flakes as needed.
Drain pasta: Drain the pasta in a colander and be sure to reserve a bit of the pasta water. Immediately transfer the pasta to the pan with the sauce. Raise the heat a little and combine, stirring with the sauce. If it's too thick, add a bit of the reserved starchy pasta water to thin it out.
Plate up the pasta: Serve the pasta and add some more chopped fresh parsley, if you like. Enjoy!