Slow Cooker Stuffed Peppers in Marinara Sauce

Name: Slow Cooker Stuffed Peppers in Marinara Sauce
Ingredients: 1 (28-ounce) can crushed tomatoes; 1 (28-ounce) can diced tomatoes; 1 (6-ounce) can tomato paste; 1 medium yellow onion, diced; 2 1/2 teaspoons minced garlic (5 cloves); 2 bay leaves; 1 tablespoon dried basil; 1 tablespoon packed brown sugar; 1 tablespoon balsamic vinegar; 1 1/2 teaspoons dried oregano; 1/2 teaspoon red pepper flakes; 1 teaspoon salt; 1/2 teaspoon freshly ground black pepper; 4 medium bell peppers (any color); 2 (15-ounce) cans black beans, drained and rinsed; 1/2 cup uncooked quinoa, rinsed; 2 medium zucchini, chopped