Preheat your oven to 350°F (175°C).
In a large skillet, heat the olive oil over medium heat. Add the diced onion and minced garlic, sautéing until the onion is translucent.
Add the mixed vegetables to the skillet and cook for about 5-7 minutes until they are tender.
In a large mixing bowl, combine the cooked shredded chicken, sautéed vegetables, cooked pasta, chicken broth, Italian seasoning, and salt and pepper. Mix well.
Transfer the mixture to a greased casserole dish. Sprinkle the shredded cheese evenly on top.
Bake in the preheated oven for 20-25 minutes, or until the cheese is melted and bubbly.
Let it cool for a few minutes before serving. Enjoy your Chicken Primavera Casserole!