I have been making my sauce this way for years. It is great with spaghetti but also makes a great base for stuff like Baked Ziti or Lasagna. It is way better than the jar stuff like Ragu or Prego.
What is needed:
Large pot with lid
4 large cans of tomato sauce (like Hunt's or something)
1 large onion
Jar of chopped garlic
Add some olive oil to the bottom of your pot and turn the heat on medium-high.
Dice your onion and put it in the pot.
Add 1 heaping tablespoon of chopped garlic and sauté until the onions are translucent.
Add the four cans of tomato sauce to the pot and stir well.
Add 1 tablespoon of parsley.
Add 2 tablespoons of oregano.
Add 1 tablespoon of basil.
Mix thoroughly and add salt and pepper to taste.
Cover the pot with lid and lower the heat to low, cook for a half hour (stir occassionally).
Add 1 heaping tablespoon of parmesan cheese, mix thoroughly and taste.
Adjust with additional seasonings as needed (if needed).
Cover and cook on low for another 45 minutes (stir occassionally) and you are done!
If you want to make it “interesting” add two cans of solid white Albacore (drained - packed in water), tastes a bit like clam sauce if that is your thing.
...that is all.