Bring a large pot of salted water to a boil. Add the penne pasta and cook according to package instructions until al dente, about 10-12 minutes. Drain and set aside.
While the pasta cooks, heat olive oil in a large skillet over medium heat.
Add the chopped onion to the skillet and sauté until translucent, about 4-5 minutes.
Add the minced garlic and cook for 1 minute until fragrant.
Add the ground turkey to the skillet. Cook, breaking it up with a spoon, until fully cooked and no longer pink, about 7-8 minutes.
Stir in the marinara sauce, dried oregano, dried basil, salt, black pepper, and red pepper flakes. Simmer the sauce with the turkey for 8-10 minutes, stirring occasionally.
Add the cooked penne pasta to the skillet and toss well to combine with the sauce and turkey.
Remove from heat and stir in the grated Parmesan cheese.
Serve the pasta hot, garnished with chopped fresh parsley.