Homemade marinara sauce is better than any jarred sauce
In a large Dutch oven over medium eat, warm the oil. Add the onion and cook 3-5 minutes until softened, then add the garlic and stir briefly.
Add the tomatoes (break up whole one), diced tomatoes or tomato sauce you are using. Rinse out cans with about 1 cup of water and add to the tomatoes. Add salt and Italian herb mix, and any left over jarred sauce you might have on hand.
Cook, stirring occasionally, about an hour. Sauce will reduce and thicken.
Stir in cheese, if using. Taste and adjust salt and pepper.
Adding jarred sauce does something to create a nice consistency of homemade sauce. It also uses up something sitting the in fridge that might go to waste!