Begin by filling a large pot with water and adding a generous pinch of salt. Bring it to a rolling boil over high heat, then add the penne pasta. Cook according to package instructions until it's just shy of al dente, typically around 8-10 minutes. Before draining, reserve about a cup of pasta water for later use. Drain the pasta and set it aside.

In a large skillet, heat 2 tablespoons of olive oil over medium heat until shimmering. Add the diced yellow onion and sauté for about 5 minutes, stirring occasionally, until the onion is soft and translucent.

Introduce the ground turkey to the skillet, breaking it apart with a spatula. Cook for approximately 6-8 minutes or until the turkey is browned. Season with salt, black pepper, Italian seasoning, and minced garlic. Stir well to combine, allowing the garlic to sauté just until fragrant, about 1 minute.

Sprinkle the all-purpose flour over the browned turkey mixture and stir for about 1 minute to coat. Gradually pour in the chicken broth and tomato sauce, mixing continuously to prevent lumps. Bring the mixture to a simmer over medium heat, allowing it to thicken for 3-5 minutes until it reaches a creamy consistency.

Gently fold the cooked penne pasta into the sauce, ensuring each piece is well-coated. Stir in the half-and-half, adjusting the thickness of the sauce with the reserved pasta water as needed.

Lower the heat to low and stir in half of the mozzarella and cheddar cheese until melted. Top with the remaining cheese, cover the skillet, and allow it to sit for a few minutes until the cheese is beautifully melted.

Once the cheese is bubbly and melted, remove the skillet from heat. Garnish with freshly chopped parsley and a sprinkle of red chili flakes for an added kick. Plate and serve warm.