Drain and rinse the chiles. Cut them up one side, seed them and open them flat. Arrange chiles in a shallow baking dish lightly coated with vegetable cooking spray. Cut the cheese and turkey into 1/2-inch strips. Fill each chile half with cheese and turkey strips. Fold over edges of chiles and place seam-side down in dish. In a medium bowl, combine flour, baking powder and salt. In a small bowl, whisk the milk and eggs. Slowly add egg mixture to flour mixture, beating until smooth. Pour over prepared chiles. Bake at 450 degrees for 15 minutes. Remove from oven and turn off heat. Sprinkle cheddar cheese over top and return to oven 1 minute to melt cheese. Makes 6 servings.