To Make Crust: Mix together 1 cup flour, baking powder, sage, and 1/4 teaspoon salt. Cut in butter or margarine until mixture is crumbly. Stir in milk. Gather dough into a ball, wrap in plastic, and allow to rest in refrigerator.
Spray a large nonstick skillet with cooking spray. Cook onions and garlic together over medium heat until soft, about 5 minutes. Add broth, potatoes, carrots, and mixed vegetables. Simmer partially covered for 12 minutes. Potatoes should be slightly undercooked.
In a small bowl, combine cream of chicken soup and flour. Mix until smooth. Add mixture to vegetables along with chicken, parsley, basil, thyme, salt, and pepper. Pour mixture into a 2 quart casserole dish.
Roll out dough to fit top of casserole dish. Lay dough over filling and prick with a fork several times.
Bake in preheated oven for 25 minutes, until crust is golden brown. Allow to sit 5 minutes before serving.
