Heat a large skillet with tall sides over medium-high heat with 2 tablespoons of butter and chicken. Cook for about 7-10 minutes or until the chicken is cooked through. Remove to a plate and set aside.
While the chicken cooks, make the stuffing. In a medium saucepan, bring the chicken broth and butter to a simmer, then remove from the heat and mix in the stuffing. Set aside.
Preheat the oven to 375 degrees F.
Add remaining 4 tablespoons of butter, onion, celery and carrots to the skillet. Cook for 5-7 minutes, or until vegetables are tender. Add garlic, nutmeg, thyme, sage, salt and pepper. Stir to combine and let cook for one minute. Sprinkle vegetables with flour and mix until combined. Let cook for another minute.
While mixing, slowly pour in the chicken broth then the milk. Simmer for a few minutes until thickened.
Remove from heat and mix in the sour cream, chicken, green beans and corn then transfer to a 9x13 inch baking dish. Spread the stuffing over the filling. Cover and bake for 30-35 minutes, or until hot and bubbly around the edges. Remove the cover and bake another 5 minutes.
Serve and enjoy!