Preheat your oven to 350°F (175°C) and prepare a 9x9 inch baking pan by greasing it with butter or lining it with parchment paper.

In a medium mixing bowl, whisk together the flour, baking powder, cinnamon, and nutmeg until well blended.

In a large bowl, cream the melted butter and brown sugar until smooth, then mix in pumpkin puree, eggs, and vanilla extract.

Gradually mix the dry ingredients into the wet ingredients, folding gently until just combined.

For a spiced swirl, mix a small portion of blondie batter with extra cinnamon and nutmeg, then swirl into the main batter.

Spread the batter evenly in the prepared pan and sprinkle with granulated sugar and cinnamon on top.

Bake for 25 to 30 minutes until edges are golden and a toothpick inserted comes out clean.

Allow to cool for 10 to 15 minutes before lifting out of the pan and cooling completely on a wire rack.