Preheat an oven to 375 degrees fahrenheit and spray a 9X13 inch baking dish with non-stick cooking spray.

Cook the stuffing mix according to the package directions and set it aside.

In a large skillet over medium high heat, melt the butter, add in the onion, celery, and carrots. Saute the vegetables until the onion is translucent, about 5 minutes. Add in the garlic and saute for 2 minutes.

Add the flour and cook, stirring, for 1 minute. Slowly add the broth, stirring constantly. Add in the heavy whipping cream and bring it all back to a gentile boil.

Add in the chicken, thyme, oregano, parsley, salt and pepper. Stir everything together until well combined.

Pour the chicken and vegetable mixture into the greased baking dish. Top the mixture with the prepared stuffing.

Bake until the stuffing on top is a golden brown and the chicken mixture is bubbling, about 30 to 35 minutes.

Remove the casserole from the oven and allow it to set at room temperature for about 10 minutes before serving.