Preheat oven to 350°F. Grease a 9x5-inch loaf pan and line with parchment.
Put the pumpkin puree in a saucepan over medium heat; cook, stirring constantly, 6-8 minutes until reduced to about 1 1/4 cups and darkened. Cool 10 minutes.
Whisk flour, baking soda, baking powder, salt, cinnamon, nutmeg, cloves, and ginger in a medium bowl.
In a large bowl, whisk both sugars with the eggs, then the oil, orange zest, and vanilla. Stir in the cooled pumpkin.
Fold dry ingredients into wet just until combined. Fold in walnuts.
Pour into the pan; sprinkle with walnuts and turbinado sugar. Bake 55-65 minutes until a toothpick comes out with moist crumbs. Tent with foil if browning too fast.
Cool in the pan 15 minutes, then lift out and cool completely before slicing.