Preheat oven to 350F and grease 9x13 inch baking dish.

Start by browning your butter. In a saute pan, heat to medium. Add butter to pan and let melt down and crackle. Whisk continuously and often during the browning period. Browning takes about 5-7 minutes. Once it is amber brown like maple syrup, turn off heat. Pour brown butter into a small bowl and let cool for a few minutes.

Meanwhile, whisk together flour, pumpkin pie spice, baking soda, and salt.

Add slightly cooled brown butter to a larger bowl. It's okay if it is still warm, just not piping hot. Whisk in brown sugar until smooth, then whisk in egg, pumpkin puree, and vanilla.

Using a spatula or wooden spoon, slowly add flour mixture to wet ingredients until all combined and dough has formed.

Stir in 1.5 cups of white chocolate chips.

Pour into bottom of greased baking dish and press into sides using your hand or spatula. Add remaining chocolate chips on top and press into dough.

Bake for 32-34 minutes or until toothpick inserted comes out clean. Let cool for at least one hour before cutting into but preferably until totally cooled.