Heat 1 tablespoon olive oil in a large saucepan over medium heat. Add 1 medium chopped onion and sauté until translucent, about 3 minutes.
Add 4 minced garlic cloves to the pan and cook 1 minute more, then stir in the 28-ounce can crushed fire-roasted tomatoes, 3 tablespoons tomato paste, 2 teaspoons chopped oregano, 1 teaspoon minced chipotle, the rosemary sprig, and a pinch of salt.
Bring the sauce to a low boil, then reduce heat and simmer about 15 minutes until it has reduced slightly; season with salt and pepper to taste.
Meanwhile, preheat the broiler and lightly spray a baking sheet with cooking spray.
In a large bowl, combine 1 pound ground turkey, pulsed whole-wheat bread crumbs, 1/4 cup grated Parmesan, 1/2 cup grated carrot, 1/2 cup finely chopped onion, 2 minced garlic cloves, 2 tablespoons minced parsley, 2 teaspoons minced thyme, 1 lightly beaten large egg, 1/2 teaspoon salt, and freshly ground black pepper; mix until just combined.
Form the mixture into 2½-inch meatballs and arrange them on the prepared baking sheet. Broil about 10 minutes until browned and almost cooked through.
Remove the rosemary sprig from the sauce and stir in 1/4 cup torn fresh basil leaves.
Add the broiled meatballs to the sauce, cover, and simmer 10 minutes more until the sauce thickens slightly and the meatballs are cooked through.
While the meatballs finish cooking, bring a large pot of salted water to a boil and cook the 16-ounce whole-wheat spaghetti according to package directions. Drain.
Return the drained pasta to the pot, add the sauce and meatballs, toss to combine, and heat through over medium heat. Divide among 6 bowls and garnish with additional parsley and about 1 tablespoon grated Parmesan per serving, if desired.
