Step 3
In 2-quart saucepan, melt butter over medium heat. Add onion; cook 2 minutes, stirring frequently, until tender. Stir in flour, salt, and pepper until well blended. Gradually stir in broth and milk, cooking and stirring until bubbly and thickened. Stir in chicken and mixed vegetables. Remove from heat. Spoon into crust-lined pie plate.