1 tablespoon pumpkin pie spice (or mix of cinnamon, ginger, and allspice)
1/2 teaspoon baking soda
2 cups mashed sweet potato or pumpkin puree
1 cup plain low-fat yogurt
3 large eggs
1 cup turbinado sugar, plus 2 tablespoons more for sprinkling
1 1/2 cups coarsely chopped walnuts
How to make it
Preheat oven to 350 degrees. Brush 12 jumbo muffin tins (each with a 1-cup capacity) with oil; set aside.
In a medium bowl, whisk flours, baking powder, pumpkin pie spice, and baking soda; set aside.
In a large bowl, whisk oil, pumpkin puree, yogurt, eggs, and 1 cup sugar to combine; add 1 cup walnuts and reserved dry ingredients. Mix just until moistened (do not overmix).
Divide evenly and spoon batter into muffin tins; sprinkle tops with remaining walnuts and sugar. Bake until a toothpick inserted in the center of a muffin comes out clean, 35 to 40 minutes. Cool 5 minutes in pan.