In a large Dutch oven, heat olive oil over medium heat.  Add the onion, carrot, celery, salt and pepper. Cook until soft, about 8 minutes, stirring occasionally.  Add garlic and bay leaves and stir until fragrant, about 1 minutes.  Push the vegetables to one side and add the tomato paste, let it toast on the bottom of the pan for 1 minute then stir into the vegetables.  

Add the tomatoes and chicken stock and bring to a boil.  Reduce the heat and simmer until significantly reduced, about 1 hour.  Discard the bay leaves. Puree the sauce in the blender (or use a hand-held immersion blender). Return the sauce to the pot.   

If you have made meatballs, add them to the sauce by gently placing a few at a time.  Let simmer together for about 15 minutes.