Boil the penne in salted water until al dente. Reserve about 1/2 cup of pasta water before draining.
In a large pan, heat the olive oil over medium heat. Add the minced garlic and red chili flakes, sautéing for about 1 minute until the garlic is fragrant but not browned.
Pour in the crushed tomatoes and season with salt. Let the sauce simmer for about 10 minutes, allowing it to thicken and the flavors to meld.
Add the drained penne to the sauce, tossing to combine. If the sauce is too thick, add a little reserved pasta water to achieve your desired consistency.
Plate the pasta, top with chopped parsley, and add Parmesan cheese if desired.