Zucchini Roll Ups with Ricotta and Roasted Tomato Sauce

Name: Zucchini Roll-Ups with Ricotta and Roasted Tomato Sauce
Ingredients: 1 yellow onion, diced; 4 garlic cloves, peeled and smashed; 1/2 lb. (250 g) cherry tomatoes; 3 Tbs. extra-virgin olive oil; 2 lb. (1 kg) heirloom tomatoes, halved crosswise; Kosher salt and freshly ground pepper; 6 fresh basil leaves, plus 1 Tbs. finely chopped basil; 8 oz. (250 g) ricotta cheese; 1/2 cup (2 oz./60 g) grated Parmesan cheese; 3 Tbs. chopped fresh flat-leaf parsley; 2 Tbs. finely chopped fresh chives; 1 tsp. grated lemon zest; 1/2 lb. (250 g) medium zucchini; 1/3 cup (1 1/2 oz./45 g) shredded mozzarella cheese