Danish Apple Pizza

12 to 16 servings. In a bowl, combine flour and salt. Cut in shortening until the mixture resembles coarse crumbs. Combine milk and egg yolk; mix well. Gradually add to dry ingredients until dough forms a ball. Cover and refrigerate for at least 1 hour. On a lightly floured surface, roll out half of pastry to fit an ungreased 13-inch pizza pan. Sprinkle with cornflakes. Top with apples. Combine sugar and cinnamon; sprinkle over apples. Roll out remaining pastry to fit top of pie. Place over apples; cut slits in top. Seal pastry and flute edges if desired. Brush with beaten egg white. Sprinkle with additional sugar if desired. Bake at 350F for 40 to 45 minutes or until golden brown. For glaze, combine confectioners' sugar, vanilla, and enough water to achieve desired consistency. Drizzle over pizza.