1. Preheat oven to 400°. Melt butter over medium heat. Sauté leeks 7 minutes. Sprinkle flour over leeks. Cook, stirring constantly, for 3 minutes. Whisk in chicken broth and next 3 ingredients; bring to a boil. Remove from heat. Add peas, corn blend, parsley, 2 teaspoons dill, and chicken. Mix well. Pour into a greased 9-inch deep pie dish.
2. Whisk together egg yolk and 1 tablespoon water, and brush underside of crust edge with egg wash. Place crust, brushed side down, over pie; crimp or use back of fork to seal rim of crust around dish. Cut 4 to 5 vents in the pastry. Brush top with egg wash, and sprinkle with remaining 1 teaspoon dill. Bake at 400° for 30 to 35 minutes or until pastry is golden brown and mixture is bubbling.