Combine apple, 1 teaspoon orange rind, 1 tablespoon orange juice, and next 3 ingredients in a medium saucepan. Cook over medium heat, stirring occasionally, 10 to 15 minutes or until apple is soft. Cool.
Unfold piecrusts, and stack together on a lightly floured surface. Roll into a 14- x 9-inch rectangle; cut pastry into 8 equal rectangles. Spoon apple mixture evenly into center of each rectangle. Starting with a short side, fold dough over filling. Press edges with a fork to seal, and prick tops. Place turnovers on an aluminum foil-lined baking sheet.
Bake at 450° for 10 minutes or until golden. Cool.
Stir together 3/4 cup powdered sugar, remaining 1/2 teaspoon grated orange rind, and remaining 1 tablespoon fresh orange juice. Drizzle over turnovers.