Heat oven to 375°F. In small bowl, mix walnuts, brown sugar and butter with pastry blender or fork until crumbly. In medium bowl, stir together apples, flour and 1/4 teaspoon cinnamon; set aside.
Unroll crusts on work surface. Cut each crust into quarters. Place about 1/4 cup apple mixture on one half of each pie crust wedge. Sprinkle with walnut mixture. Fold untopped half over filled half (foldovers will be full). Press edges with fork to seal. Prick top with fork. Place on ungreased large cookie sheet.
Bake 22 to 28 minutes or until golden brown. Cool 10 minutes. Meanwhile, in small bowl, stir together glaze ingredients until smooth. Drizzle over foldovers. Cool completely, about 30 minutes.