In a saucepan over medium hight heat, melt and stir butter until it turns golden brown and smells fragrant and toasty. Remove from heat to cool while you mix up the rest of the ingredients.
Preheat oven to 350 degrees. In a bowl, whisk together the flour, pumpkin pie spice, baking powder, baking soda, and salt. Set aside.
In another bowl, whisk together the pumpkin puree, sugar, brown sugar, and browned butter. Add eggs and whisk together well. Add dry ingredients and whisk until combined.
Line a standard size loaf pan with parchemt paper, and lightly spray or butter the parchment. If you don't have parchment, butter and flour the pan to prevent sticking. Spread batter evenly in pan. Bake for about 48 minutes, or until a toothpick inserted into the center comes out clean. Baking times can vary depending on your oven. Remove from oven, allow to cool 30 minutes, (remove from pan after about 15 minutes) then begin making the glaze.