Chicken Pot Pie Casserole

Preheat oven to 375°. Melt butter in a large pot over medium heat and saute onion and celery until soft, about 5 minutes. Add garlic and cook 1–2 more minutes. Stir in flour and cook 2–3 minutes, coating vegetables. Gradually whisk in 1/2 cup milk, then stir in remaining milk and chicken broth until smooth. Reduce heat to medium-low. Stir in spices, cooked chicken and frozen peas and carrots. Simmer 5 minutes. Pour into a greased 9×9-inch baking dish. Top with pie crust. Crimp crust edges, cut slits for steam and brush with egg wash. Bake 35–40 minutes, until crust is golden and filling bubbles. Let cool 10 minutes before serving. Serves 6.