Preheat your oven to 375°F (190°C). Cook the pasta according to package directions until al dente, then drain and set aside. While the pasta cooks, heat olive oil in a large skillet over medium-high heat. Season the chicken cubes with salt, pepper, and Italian seasoning, then cook until golden brown and cooked through, about 6-8 minutes. Remove chicken from skillet and set aside.

In the same skillet, add the chopped onion and cook until softened, about 3-4 minutes. Add the minced garlic and cook for another minute until fragrant. Reduce heat to medium-low and stir in the pesto, heavy cream, and chicken broth. Bring to a gentle simmer, then stir in 1 cup of mozzarella cheese and all the Parmesan cheese until melted and smooth.

Add the cooked pasta and chicken to the skillet with the sauce, stirring gently to coat everything evenly. If your skillet isn't oven-safe, transfer the mixture to a 9x13 inch baking dish. Top with the remaining 1 cup of mozzarella cheese.

Bake for 20-25 minutes, or until the cheese is melted and bubbly with golden spots. For extra browning, you can broil for the last 2-3 minutes. Let the pasta bake rest for 5 minutes before serving to allow the sauce to thicken slightly.