Heat the oven to 350°F with a rack in the middle position. Mist a 9-by-5-inch loaf pan with cooking spray, then line it with an 8-by-14-inch piece of kitchen parchment, allowing the excess to overhang the long sides of the pan.

In a medium bowl, whisk together the flour, baking powder, baking soda and salt. Reserve 1 tablespoon of the chopped pistachios for sprinkling and add the remainder to the flour mixture along with the candied ginger. Toss to combine.

In a large bowl, whisk the eggs. Add the carrots, brown sugar, buttermilk, oil, 110 grams (⅓ cup) of the tahini and 2 teaspoons orange zest, then stir with a silicone spatula until well combined. Add the flour mixture and mix just until evenly moistened. Scrape the batter into the prepared pan and smooth the top. Bake until a toothpick inserted at the center of the loaf comes out clean, 50 to 55 minutes.

Cool in the pan on a wire rack for about 15 minutes. Lift the loaf out of the pan using the parchment and set it directly on the rack. Let cool completely.

Remove the parchment liner under the loaf. In a medium bowl, combine the powdered sugar, the remaining 2 tablespoons tahini, the remaining 1 teaspoon orange zest and the orange juice. Whisk until smooth. Pour the glaze onto the loaf and smooth with a spatula, then sprinkle with the reserved pistachios. Let stand for about 15 minutes before slicing.