Preheat oven to 375°F. Line the bottom of a spring form or tart pan with parchment paper. Using your fingers, lightly grease the pan and paper with butter.
In a medium sized mixing bowl, mix flours (break up any lumps with your fingers), baking soda, baking powder, salt, and pumpkin pie spice with a whisk until well combined.
In a small bowl, mix the pumpkin, eggs, honey, and vanilla extract until well blended.
Add the wet ingredients to the dry ingredients and stir until well mixed (the batter is pretty thick), spread into prepared pan with a spatula.
Bake for 20 minutes while preparing the maple glaze.
Pour the maple syrup into a medium skillet and cook over medium heat until bubbly. Stir in the walnuts and pumpkin pie spice; continue stirring until syrup thickens slightly. When the first 20 minutes of baking is done, remove the cake from the oven and drizzle the maple-walnut glaze over the cake, gently spreading the walnuts around.
Return the cake to the oven and bake for 10 more minutes or until a toothpick inserted in the center comes out clean.
Allow cake to cool in the pan on a wire rack for 10 minutes. Run a sharp knife around the edge of the cake to release from pan, and remove pan sides from cake. Cool completely on wire rack. Slice and serve.
Notes
Recipe Variation:Substitute pepitas for the walnuts