Line an 8x8” or 9x9” baking pan with parchment paper so that it covers the bottom and comes up two of the sides. This will make it easier to lift out the bars for cutting
To make the crust, first soak the pitted Medjool dates and raisins in boiling water for 3-5 minutes to soften them. Drain the water and add the dates and raisins into a food processor along with the remaining crust ingredients. Process on high speed for 3-5 minutes, until the mixture begins to clump together slightly. It should hold together when pinched with your fingers. If it is too crumbly, add a tiny bit of the date/raisin soaking water at a time and continue to process.
Press the crust dough firmly and evenly into the parchment-lined baking pan. Place the crust in the fridge or freezer while you prepare the filling.
To make the filling, combine all filling ingredients in the food processor and blend on high until smooth. Adjust the sweetness and pumpkin pie spice to your taste if desired.
Pour the filling into the prepared crust and smooth out the top evenly. Cover loosely with plastic wrap and refrigerate for 5-6 hours or freezer for 2-3 hours so that the bars can firm up. You can also make these a day ahead and chill in the fridge overnight.
When ready to serve, lift the bars out of the pan using the parchment paper as handles, then slice with a sharp knife, wiping the knife clean between cuts. It is much easier to cut the bars into squares while they are very cold. Serve chilled and store leftover bars in an airtight container in the refrigerator or freezer.