Begin by bringing a large pot of salted water to a rolling boil over high heat. Add the penne pasta and cook it until just shy of al dente, about 8 to 10 minutes. Reserve 1 cup of the starchy pasta water before draining the pasta in a colander. Set the cooked pasta aside for later, allowing it to cool slightly as you prepare the sauce.

In a large skillet, heat the olive oil over medium heat until shimmering. Add the diced yellow onion and sauté for about 5 minutes, stirring frequently until the onion becomes soft and translucent.

Add the ground turkey to the skillet, breaking it apart with a wooden spoon as it cooks. Allow it to brown for 6 to 8 minutes, stirring occasionally. Season generously with salt, black pepper, and Italian seasoning for flavor. After the turkey is no longer pink, mix in minced garlic and continue to cook for another minute until fragrant.

Sprinkle the all-purpose flour over the browned turkey and stir well to combine, cooking for about 1 minute to remove the raw flour taste. Gradually pour in the chicken broth and tomato sauce, stirring constantly until the mixture thickens, which should take about 3 to 5 minutes.

Gently fold the drained penne pasta into the skillet with the sauce, ensuring each piece is well-coated. Pour in the half-and-half along with a splash of the reserved pasta water, stirring to achieve your desired creaminess. Let everything simmer together for a couple of minutes.

Reduce the heat to low and fold in half of the mozzarella and cheddar cheese. Stir until the cheese melts smoothly into the sauce, about 2 to 3 minutes. Sprinkle the remaining cheese over the top, covering the skillet and letting it melt into a bubbly, delicious layer.

Once the cheese is melted and bubbly, remove the skillet from the heat. Garnish with freshly chopped parsley and a sprinkle of red chili flakes if you like some heat. Serve warm and enjoy.