1. Preheat oven to 425 F. Using a 9" pie pan, make pie crust as directed on box.
2. In a 2 qt saucepan, melt butter over medium heat. Add onion, cook 2 minutes, stirring frequently. Stir in flour, salt and pepper until well blended. Gradually stir in broth and milk, cooking and stirring until bubbly and thickened.
3. Stir in chicken and mixed vegetables. Remove from heat. Spoon chicken mixture into crust lined pan. Top with second crust. Seal edge and flute crust. Cut slits in several places in top crust to vent steam.
4. Bake for 30 - 40 minutes or until crust is golden brown. If necessary cover the edge of crust with foil to prevent it from browning too much. Let stand 5 minutes before serving.