Preheat the oven to 350° F. Line a 9×13 inch baking dish with parchment paper.Add the butter to a medium pot set over medium heat. Allow the butter to brown, until it smells toasted, about 2-3 minutes. Remove from the heat and pour into a large bowl. Let cool 5 minutes. Add the brown sugar, pumpkin butter, maple, eggs, and vanilla. Mix in the flour, baking powder, baking soda, cinnamon, ginger, and salt, mixing until just combined. Fold in the white chocolate. Spread the dough out into the prepared dish.Bake for 25-30 minutes, just until set in the center. Let cool.Meanwhile, make the glaze. Add the butter to a small pot set over medium heat. Allow the butter to brown lightly until it smells toasted, about 2-3 minutes. Remove from the heat and whisk in the powdered sugar, espresso, vanilla, and a pinch of salt. Drizzle the glaze over the bars. Let set for 5 minutes. Cut into bars, snack, and enjoy!