Preheat the oven to 350°F. Line a 9x13-inch baking pan with foil or parchment paper, leaving an overhang.
In a large bowl combine the flour, cinnamon, ginger, nutmeg, allspice, and salt.
In another medium bowl whisk together the butter, brown sugar, egg, vanilla, and pumpkin.
Add the butter mixture to the flour mixture, stirring until just combined. Stir in the chocolate chips. Pour the batter into the prepared pan.
Bake for 35 minutes, or until a cake tester inserted into the center comes out clean. Be careful not to overbake. Set the pan on a wire rack to cool completely before cutting into squares. Store in an airtight container at room temperature for up to 5 days.
Notes
These blondies taste even better the day after they're baked!