Preheat the oven to 375°F (190°C). Grease a 9x13 inch baking dish.
In a large skillet over medium heat, cook the cubed chicken until browned and cooked through. Season with salt, pepper, and Italian seasoning. Transfer to the prepared baking dish.
In the same skillet, sauté the sliced zucchini until slightly softened, about 3-4 minutes. Add the minced garlic and cook for an additional minute. Transfer the zucchini mixture to the baking dish with the chicken.
In a bowl, whisk together the heavy cream, pesto sauce, and grated Parmesan cheese. Pour the mixture over the chicken and zucchini in the baking dish. Top with the shredded mozzarella cheese and chopped sun-dried tomatoes.
Bake for 20-25 minutes or until the cheese is melted and bubbly. If desired, broil for 2-3 minutes to brown the cheese.