2½ cups (313 grams) all-purpose flour1 tablespoon plus 2 teaspoons pumpkin pie spice2 teaspoons (10 grams) baking powder2 teaspoons (6 grams) kosher salt½ teaspoon ground black pepper1¼ cups (181 grams) chopped dried dates, divided1 (15-ounce) can (425 grams) pumpkin¾ cup (150 grams) granulated sugar⅔ cup (149 grams) neutral oil, plus more for scoring½ cup (110 grams) firmly packed dark brown sugar2 large eggs (100 grams), room temperature2 teaspoons (8 grams) vanilla extract1 tablespoon (7 grams) confectioners’ sugar
Preheat oven to 325°F (170°C). Spray an 8½x4½-inch loaf pan with baking spray with flour. Line pan with parchment paper, letting excess extend over all sides of pan.
In a medium bowl, whisk together flour, pie spice, baking powder, salt, and pepper. Add 1 cup (145 grams) dates, tossing to coat.
In a large bowl, whisk together pumpkin, granulated sugar, oil, brown sugar, eggs, and vanilla until smooth. Add flour mixture, and gently fold with a rubber spatula until combined. Pour batter into prepared pan, spreading with a small offset spatula. Firmly tap pan on a kitchen towel-lined counter to settle batter. Wipe excess batter off offset spatula, and dip into neutral oil; with spatula, starting at one short side of pan, score a 3- to 4-inch line lengthwise down center of batter.
Bake until a wooden pick inserted in center comes out with a few moist crumbs and an instant-read thermometer inserted in center registers 205°F (96°C), 1½ hours to 1 hour and 40 minutes. Let cool in pan for 10 minutes. Using excess parchment as handles, remove from pan, and let cool completely on a wire rack.
In a small bowl, toss together confectioners’ sugar and remaining ¼ cup (36 grams) dates to coat. Sprinkle dates onto cooled loaf, and dust top of loaf with any remaining confectioners’ sugar. Store in an airtight container for up to 3 days.