Place the onion, garlic, tomatoes, tomato paste, olive oil, bay leaves, basil, oregano, brown sugar, salt, pepper, and crushed red pepper in the slow cooker. Stir and put the lid on. Set the slow cooker to low and cook for 8 hours.

Remove the lid on the slow cooker, stir the sauce, and remove the bay leaves. If you don't like a chunky sauce, use a hand blender to puree the sauce. You can also transfer the sauce to a blender if you don't have a hand blender. Just be careful if the sauce is hot. Taste and season with additional salt and pepper, if necessary. This sauce is great with your favorite pasta, vegetables, layered between lasagna, with meatballs, on top of chicken or eggplant parmesan, or served as a dipping sauce for garlic knots or pizza rolls.

Note-you can cook on high for 2-4 hours, but I think the sauce is best cooked on low. It allows the sauce time to simmer and develop a rich flavor. This sauce freezes beautifully! Cool completely and pour the sauce into freezer bags or freezer containers. Freeze for up to 3 months.