In a large bowl, beat the pumpkin, sugar, milk, eggs, orange juice, oil, maple flavoring and vanilla until well blended. Combine the flours, flaxseed, orange peel, baking powder, cornstarch, poppy seeds, pie spice, salt and baking soda; gradually beat into pumpkin mixture until blended.
Transfer to a greased and floured 10-in. fluted tube pan. Bake at 350° for 55-60 minutes or until a toothpick inserted near the center comes out clean. Cool for 10 minutes before removing from pan to a wire rack to cool completely.
In a small bowl, whisk the confectioners' sugar, orange peel and enough juice to achieve desired consistency. Drizzle over cake. Yield: 14 servings.