Cook the pasta shells according to package instructions until al dente. Drain and set aside.
Heat olive oil in a large skillet over medium heat. Add diced chicken and season with salt, pepper, and garlic powder. Cook for 5-7 minutes until golden brown and fully cooked. Remove from skillet and set aside.
In the same skillet, melt the butter and sauté minced garlic for about 1 minute until fragrant.
Pour in the heavy cream and chicken broth, stirring well. Add Italian seasoning, Parmesan cheese, and mozzarella cheese, stirring until the sauce becomes smooth and creamy.
Return the cooked chicken to the sauce, mixing to coat evenly.
Stuff each cooked pasta shell with the creamy chicken mixture and arrange them in a baking dish.
Sprinkle additional mozzarella cheese over the top and bake at 375°F (190°C) for 10 minutes, or until the cheese is melted and bubbly.
Garnish with fresh parsley and serve warm.