Heat oven to 350°F. Cook and drain pasta as directed on package. Rinse with cool water; drain.
Heat the olive oil in a large skillet over medium high heat, add the onions and sauté for 5-6 minutes until soft. Add the garlic, red pepper flakes and Italian seasoning and stir to combine, for 30 seconds.
Add the ground turkey and break apart using a wooden spoon. Sauté for 6-8 minutes until no pink remains. Add the marinara sauce and stir to combine. Reduce heat and simmer for 10 minutes.
Spread 1 cup of the pasta sauce in bottom of baking dish. Stuff each pasta shell with the ground turkey mixture. Arrange shells, filled sides up, on sauce in baking dish.
Cover dish with foil; bake 15 minutes. Sprinkle with parmesan and top with torn mozzarella. Bake uncovered 5-10 minutes longer or until cheese is melted. Garnish with tons of fresh basil and serve.
Notes
If you have kids, this is a fun one to get them involved in as they can help stuff the shells with the ground turkey meat mixture!!