Begin by bringing a large pot of salted water to a rolling boil. Add the penne pasta and cook according to package directions until al dente. Drain and set aside.
In a large skillet over medium heat, heat the olive oil. Add the chopped onion and sauté for about 3-4 minutes, until it becomes translucent.
Next, add the ground turkey to the skillet. Cook it thoroughly, breaking it apart as you go, and season it with salt, black pepper, and the Italian seasoning.
Sprinkle the flour over the turkey mixture, stir well to combine, and cook for an additional minute to eliminate the raw flour taste.
Pour in the chicken broth and tomato sauce, stirring continuously to form a smooth mixture. Bring it to a gentle simmer.
Lower the heat, then gently stir in the half-and-half. Gradually add the mozzarella and cheddar cheeses, stirring until the cheeses are melted and the sauce is creamy.
Finally, add the cooked penne to the cheese sauce, tossing to ensure every piece of pasta is coated. Sprinkle with red chili flakes and garnish with fresh parsley before serving.