Prepare the Pasta and Chicken: Cook the penne pasta according to package directions until al dente. Drain and set aside. Meanwhile, season chicken cubes with salt, pepper, and Italian seasoning. In a large skillet, heat olive oil over medium-high heat and cook chicken until golden brown and cooked through, about 6-8 minutes.

Create the Creamy Pesto Sauce: In the same skillet, add diced onion and sauté until translucent. Add minced garlic and cook for 30 seconds until fragrant. Reduce heat to low and stir in pesto sauce and heavy cream.

Combine All Ingredients: Add the cooked pasta, chicken, and cherry tomatoes to the skillet. Toss everything together until well coated with the creamy pesto sauce. Transfer the mixture to a greased 9x13 inch baking dish.

Add Cheese Topping: Sprinkle the shredded mozzarella and Parmesan cheeses evenly over the top. For extra golden-brown perfection, you can add a light drizzle of olive oil over the cheese.

Bake to Perfection: Bake in a preheated 375°F (190°C) oven for 20-25 minutes, or until the cheese is melted and bubbly, and the edges are golden brown. Let it rest for 5 minutes before serving.