Fill a large pot with salted water and bring it to a rolling boil. Add the penne pasta and cook according to package directions for 8–10 minutes until just shy of al dente. Reserve 1 cup of pasta water, then drain and set aside.

In a large skillet, heat olive oil over medium heat. Add diced yellow onion and sauté for about 5 minutes until softened and translucent.

Add ground turkey to the skillet and cook for 6–8 minutes. Season with salt, black pepper, and Italian seasoning. Stir in garlic and cook for an additional minute.

Sprinkle flour over the turkey and mix well. Gradually add chicken broth and tomato sauce while stirring continuously. Allow to simmer for 3–5 minutes.

Gently fold in the cooked penne pasta and stir in half-and-half, adding reserved pasta water as needed.

Stir in half of the mozzarella and cheddar cheese until melted. Top with remaining cheese, cover, and heat on low until fully melted.

Remove from heat, garnish with parsley and red chili flakes, then serve warm.