Heat the oven to 350° and line an 8-inch square baking dish with parchment, leaving some overhang.
In a medium bowl, whisk together the flour, pumpkin spice, and salt. In a small bowl, mix the melted butter with the sugars until smooth. Add the egg and vanilla and whisk until smooth. Add the pumpkin purée and stir to incorporate.
Use a rubber spatula to fold in the flour mixture until no dry spots remain, taking care not to over-mix. Fold in the dark chocolate chips and, if using, the almond paste. Transfer the batter to the prepared pan and spread out evenly.
Bake for 25 to 30 minutes, until the blondies lose their raw shine and a cake tester or toothpick into the center comes out clean.