In a small saucepan, heat the butter over low heat. Once melted, allow to simmer for approximately 20 minutes to brown the butter. Stir occasionally. Allow to cool to room temperature.

Preheat the oven to 350 degrees. Spray or line a 13x9 or similar sized baking dish and set aside.

In the bowl of a stand mixer, combine the cooled brown butter (and all the brown bits on the bottom of the pan!) and the brown sugar. Mix to combine.

Add in the pumpkin pie spice, vanilla, salt, baking powder, egg and pumpkin puree. Mix well, scraping the sides often.

Add in the flour and mix on low until combined. Scrape the bottoms and sides, mix again.

Fold in the white chocolate chips.

Transfer the batter to the prepared pan and spread evenly.

Bake in the preheated oven for 30-35 minutes or until the center is set and the edges are slightly golden brown.

Allow to cool. Slice and serve.