Dough:
1 cup (227 grams) unsalted butter3¾ cups (469 grams) all-purpose flour2 teaspoons (4 grams) ground cinnamon1½ teaspoons (7.5 grams) baking powder1½ teaspoons (7.5 grams) baking soda1¼ teaspoons (3.75 grams) kosher salt¼ teaspoon ground nutmeg¼ teaspoon ground cloves1 (15-ounce) can (425 grams) pumpkin2⅔ cups (587 grams) firmly packed light brown sugar*1 tablespoon (13 grams) vanilla extract
Topping:
½ cup (100 grams) granulated sugar1 tablespoon (6 grams) ground cinnamon2 tablespoons (16 grams) all-purpose flour
Preheat oven to 325°F (170°C). Lightly spray a 13×9-inch baking pan with baking spray with flour. Line pan with parchment paper, letting excess extend over sides of pan.
For dough: In a medium light-colored skillet, melt butter over medium heat. Cook, stirring or swirling skillet frequently, until butter turns a medium-brown color and has a nutty aroma. Pour butter into a large heatproof bowl, and let cool for 10 to 15 minutes.
In a medium bowl, whisk together flour, cinnamon, baking powder, baking soda, salt, nutmeg, and cloves.
Whisk pumpkin, brown sugar, and vanilla into browned butter until well combined. Gradually stir in flour mixture until just combined and no dry streaks remain. Spread half of batter into prepared pan.
For topping: In a small bowl, whisk together granulated sugar and cinnamon.
In another small bowl, whisk together flour and half of cinnamon sugar. Sprinkle flour mixture onto batter. Spoon remaining batter onto flour mixture, and gently spread into an even layer. Sprinkle with remaining cinnamon sugar.
Bake until a wooden pick inserted in center comes out with a few moist crumbs, 45 to 50 minutes. Let cool completely in pan on a wire rack. Using excess parchment as handles, remove from pan, and cut into bars. Store in an airtight container for up to 3 days.