In a large bowl, combine the flour, baking powder, 2 cups of the sugar, oil, eggs, orange juice, salt and vanilla. Beat until thoroughly combined. In another bowl, toss apples with cinnamon and remaining sugar. Spread one-third of batter in a greased 10-in. tube pan. Cover with half of the apples. Repeat layers. Spoon remaining batter over top.
Bake at 350° for 1-1/2 hours or until a toothpick inserted near the center comes out clean. Cool for 20 minutes before removing from pan to a wire rack to cool completely. Just before serving, dust with confectioners' sugar if desired. Yield: 12-16 servings.