Blend tomatoes, tomato paste and half of the basil leaves in food processor or blender to desired consistency (chunky or smooth). You may need to do one can of tomatoes at a time.
Heat a large pot over medium heat. Add olive oil, then onions and garlic. Saute for a few minutes until onion starts to become translucent.
Add all spices to the pot, stir around until fragrant (about 30 seconds).
Add blended tomato mixture to the pot and one cup of water.
Simmer uncovered for at least 30 minutes. I usually let it go for about an hour and a half. Taste the sauce to see if it needs more salt. Garnish with remaining basil.
Notes
I've noticed there is a lot of controversy over when you should add the basil to your sauce. I like to cover all my bases and prefer the flavor of adding basil when you cook and adding basil at the end. Feel free to do it whichever way you prefer!
Recipe by Savor and Glow at https://savorandglow.com/homemade-marinara-sauce/