Preheat oven to 350˚F. Coat two standard donut pans with cooking spray.
In a large bowl, combine the flour, baking soda, salt, cinnamon, nutmeg, and ginger.
In a medium bowl, whisk the eggs, and add the pumpkin, 1/2 cup of the maple syrup, vanilla, yogurt, and oil. Mix until well combined.
Add the pumpkin mixture to the dry ingredients and stir until combined. Don’t overmix.
Spoon the batter into the donut pans, filling to about 1/4″ shy of the rim, and making sure the center post is clear.
Bake for 12 to 14 minutes. Remove donuts from oven and allow to cool in the pan for 5 minutes on a wire rack. Remove donuts from pan and cool further.
To make the glaze, sift the powdered sugar into a small bowl. Add the 2 tablespoons of maple syrup and the milk and stir until smooth. Frost each donut and top with chopped walnuts.NOTE: For less added sugar, omit the glaze, and add the walnuts to the batter. If desired, coat warm donuts in maple sugar or a sugar-cinnamon mixture.