1(8-ounce) package manicotti shells (14 shells), cooked until al dente and drained
To make sauce, heat oil in a large Dutch oven. Add onion and bell pepper; sauté 10 minutes. Add tomatoes, salt and sugar; simmer over medium-low heat 1 to 2 hours, until thickened. Add remaining ingredients and cook 5 minutes.
Preheat oven to 375F.
Heat oil in a large skillet. Add squash and sauté until browned, about 7 minutes. Combine ricotta, egg, salt, cheese and herbs. Stir in squash. Stuff manicotti with squash mixture. Place in baking pan and cover with 3 cups sauce. (You’ll have sauce left over.) Bake 30 minutes.