In a large skillet, heat a tablespoon of oil over medium heat. Add bite-sized pieces of chicken, season with salt and pepper, and cook for about 10 minutes, stirring occasionally, until the chicken is no longer pink. Transfer the chicken to a plate and set aside, keeping the flavorful drippings in the skillet.

In the same skillet, melt two tablespoons of butter over medium heat. Add chopped onions and sauté for about 2 minutes, stirring until softened and fragrant.

Stir in your frozen mixed vegetables, allowing them to heat through for about 3-4 minutes.

Sprinkle in three tablespoons of flour and cook for an additional 2 minutes, stirring constantly.

Gradually whisk in 2 cups of chicken broth, followed by one cup of milk. Cook until it thickens, about 5-7 minutes.

Once thickened, return the cooked chicken to the skillet and gently fold it into the creamy vegetable mixture.

Prepare the cornbread mix according to package instructions, then pour the cornbread batter evenly over the chicken mixture in the baking dish.

Preheat your oven to 400°F (200°C) and bake for 22-26 minutes, or until the cornbread topping is firm and golden brown.

Once baked, remove the Cornbread Casserole from the oven and let it rest for about 5 minutes before serving.