In a large pot over medium heat, melt the 2 tablespoons of unsalted butter. Add the finely chopped onion, diced celery, and carrots. Sauté these ingredients for about 5-7 minutes, or until the onions become translucent and the vegetables are tender.
Stir in the peas and corn, cooking for an additional 2 minutes until they are warmed through.
Sprinkle the ¼ cup of all-purpose flour over the sautéed vegetables, stirring to coat evenly. Cook this mixture for 1-2 minutes to cook out the raw flour taste, stirring constantly.
Gradually pour in the 4 cups of chicken broth while continuously stirring to avoid any lumps from forming. Bring the mixture to a gentle simmer.
Once the broth mixture is simmering, add 1 cup of heavy cream, along with the garlic powder, onion powder, dried thyme, salt, and black pepper. Stir well to combine and allow the sauce to thicken, which should take about 5 minutes.
Gently fold in the shredded chicken, making sure it is evenly distributed throughout the creamy vegetable mixture.
Carefully pour the chicken and vegetable mixture into a greased 9x13 inch casserole dish, spreading it out evenly.
Tear the biscuits into quarters and scatter them evenly over the surface of the casserole for a delightful topping.
Place the casserole dish in the preheated oven and bake for 25-30 minutes, or until the biscuits are golden brown and the filling is bubbling hot.
Once baked, remove the casserole from the oven and allow it to cool slightly for about 5-10 minutes before serving.
Notes
Serve directly from the casserole dish, garnished with a sprinkle of fresh parsley for a burst of color. Pair it with a refreshing side salad to complement this hearty dish! Enjoy!