1. Preheat oven to 350°F (175°C) and line an 8×8-inch pan with parchment paper.

2. Melt butter in a light-colored saucepan over medium heat, stirring until browned and nutty in aroma, about 5 minutes. Pour into a bowl and let cool 10 minutes.

3. In a large bowl whisk cooled brown butter with granulated sugar and brown sugar until smooth.

4. Add pumpkin puree, egg, and vanilla; mix until combined.

5. In another bowl whisk flour, baking powder, salt, cinnamon, and nutmeg.

6. Fold dry ingredients into wet until just combined.

7. Reserve half the batter and spread the other half into the pan.

8. Mix topping sugar with cinnamon and sprinkle half over the batter in the pan.

9. Drop remaining batter by spoonfuls over topping and gently smooth.

10. Sprinkle remaining cinnamon sugar evenly.

11. Bake 25–30 minutes until edges are golden and a toothpick yields moist crumbs.

12. Cool 20 minutes in pan, then lift out with parchment and cut into 16 bars.