1. Preheat oven to 350°.
2. Coat a nonstick skillet with cooking spray; add margarine. Place over medium-high heat until margarine melts. Add mushrooms and next 3 ingredients; cook 5 minutes or until vegetables are tender, stirring often. Stir flour, dry mustard, and thyme into broth; add to vegetable mixture. Cook, stirring constantly, 2 to 3 minutes or until mixture is bubbly; stir in turkey. Spoon mixture into a 9-inch pie plate coated with cooking spray.
3. Place baking mix in a medium bowl. Combine egg white, milk, and Dijon mustard; add to baking mix, stirring just until baking mix is moistened. Pour over turkey mixture. Bake at 350° for 35 minutes or until golden. Serve immediately.