1. Preheat oven to 350 degrees F. Butter a 9x13-inch baking pan and line with parchment paper, leaving an overhang on both sides.
2. In a medium bowl whisk together the flour, cinnamon, ginger, nutmeg and salt; set aside.
3. In a large bowl whisk together the sugar and butter. Add the eggs and vanilla extract and whisk until combined. Add the pumpkin and whisk until thoroughly combined. Add the flour mixture and, using a rubber spatula, gently stir or fold the flour into the pumpkin mixture until just combined.
4. Scraped the batter into the pan and smooth the top. In a small bowl, stir together the granulated sugar and cinnamon, and then sprinkle evenly over the top of the batter. Bake for about 30 minutes, or until a thin knife inserted into the center has just a few moist crumbs on it. Cool completely and then, using the parchment as handles, lift out of the pan and cut into 24 squares. Store at room temperature in an airtight container.