Preheat oven to 350° and place oven rack in middle position. Grease and line an 8X8 baking pan with parchment paper. Set aside.
In the bowl of a stand mixer using the paddle attachment or using a hand mixer add the melted butter, brown sugar and granulated sugar. Mix on medium speed for two minutes. Add the egg, egg yolk and vanilla extract and mix for another minute. Measure out the 1/2 cup of pumpkin puree and place in a bowl or on a plate lined with several paper towels. Squeeze the excess moisture out using the paper towels. Scrape the pumpkin off of the paper towels and into the butter mixture. Mix for 30 seconds until combined, scraping down the bowl.
In a separate bowl whisk together the all purpose flour, baking soda, baking powder, cinnamon, espresso powder, ground ginger and salt. Whisk to combine. Add to the wet ingredients and mix on the lowest speed for about 30 seconds until just combined. Use a wooden spoon or spatula to fold in the chopped white chocolate (can substitute with one cup of white chocolate chips). Pour the batter into the prepared baking pan and using the wooden spoon or spatula press towards the edges and into an even layer.
Bake in the preheated oven for 16-18 minutes until the center is set and a toothpick inserted into the middle comes out clean or has a few moist crumbs. Allow to cool in the pan on a wire rack for ten minutes. Then, using the parchment paper, remove the bars from the pan and place directly on the wire rack to cool completely.
Vanilla espresso glaze
Once the bars are completely cooled make the glaze. In a bowl use a whisk to mix together the powdered sugar, espresso powder and heavy cream. Whisk until it is smooth and there are no lumps. It should be pourable but not super thin and runny. Drizzle over your pumpkin spice latte bars using either a fork or whisk, or using a plastic ziploc bag with one of the corners cut off. Enjoy!
Notes
Store in an airtight container for 2-3 days. It is essential to squeeze out the moisture in the pumpkin before adding. If using a different sized pan the baking times will vary. Espresso powder is usually found in a small jar in the baking aisle.