Preheat oven to 400°F. Cook the fettuccine according to package directions. Drain and set aside.
In a large bowl. combine the turkey, 1/4 cup of the onion, the breadcrumbs, 2 Tbs. Parmesan, 1/8 tsp. salt, and pepper. Mix until thoroughly combined; roll the turkey mixture into thirty-six 1-inch balls. Transfer meatballs to a baking sheet. Bake 12 to 15 minutes or until no longer pink.
Meanwhile, in a medium saucepan, heat the oil over medium-high heat. Add remaining 1/4 cup onion and the garlic. Reduce heat to medium and cook until tender, 6 to 8 minutes. Add the tomatoes and remaining 1/8 tsp. salt plus pepper. Bring to a simmer and cook, uncovered, until the sauce thickens slightly, about 10 minutes, stirring occasionally.
Add the reserved pasta to the tomato sauce, and toss to combine; heat through. Serve the pasta topped with the meatballs, basil, and additional Parmesan cheese.