In a large sauce pan over medium low heat add oil and onion. Sweat onion for 2-3 minutes. Add garlic and continue to cook till onion is soft. Be careful not to let the garlic turn brown. Add tomatoes,one can of water, thyme, pepper flakes, salt and pepper.
Bring to a boil reduce heat and simmer for about 30 minutes or till sauce has thickened. Add the cheese stir and check for seasoning. When you add the cheese the sauce will thicken up some. If its to thin continue cooking. The thickness of the sauce is up to you.If sauce becomes to thick thin it out with pasta water when you cook you pasta.
Make this sauce early in the day or the day before as it gets better with age.
This recipe also can be used as a base to add meat balls or other ingredients.