Saute mushrooms sprinkled with garlic powder in butter. Blend cornstarch and milk and add to mushrooms. Cook and stir until mixture thickens and bubbles and continue cooking 1 minute longer. Stir in other ingredients.

Pour into pastry lined deep dish pie plate. Top with second crust and seal edges with fork. Cut steam vents in top.

Bake at 375 for 35 minutes or until browned.