1. Preheat oven to 425 degrees F. Prepare pie crusts as directed on package for two-crust pie using 9 inch pie pan.
2. Melt margarine in medium saucepan over medium heat. Add onion; cook 2 minutes or until tender. Add flour, salt, and pepper, stir until well blended. Gradually stir in broth and milk, cooking and stirring until bubbly and thickened. Add chicken and mixed vegetables; mix well. Remove from heat.
3. Spoon chicken mixture into crust-lined pan. Top with second crust, seal edges and flute. Cut slits in several places in top crust.
4. Bake for 30 to 40 minutes or until crust is golden brown. Let stand 5 minutes before serving.