Instructions

1. Preheat the oven to 325 degrees F. Line a 9-inch square baking pan with at least 1 3/4-inch or higher sides (preferably aluminum but glass will work, too) with two strips of foil that overhang on all four sides (to easily lift out the squares after baking/cooled). You can omit the foil step and lightly grease the pan with nonstick cooking spray if you don't want to lift out the bars after baking.
2. For the crust, pulse 26 of the Oreo cookies (reserve the others for topping) in a blender or food processor until they are fine crumbs. Add the butter and pulse until the crumbs are wet and sandy in texture. Press the mixture firmly and evenly into the bottom of the prepared pan.
3. Bake the crust for 10 minutes.
4. For the filling by beating the cream cheese and sugar with an electric mixer (handheld or stand) until light and fluffy. Add the pumpkin, eggs, flour, vanilla, salt, cinnamon, ginger, nutmeg and cloves and mix until smooth. Pour the filling onto the crust and spread evenly.
5. Bake for 50-60 minutes until the sides are set but the center (about a 4-inch radius in the middle) still jiggles slightly.
6. Remove the bars from the oven but leave it on.
7. Whisk together the sour cream and powdered sugar for the topping and spoon it in dollops across the top of the bars (if you pour it all into the middle, it will be hard to spread). Quickly spread it evenly across the top. Bake the bars for another 10-15 minutes until the edges of the sour cream topping are set.
8. Let the bars cool on a rack for an hour or so. Cover loosely with foil or plastic wrap and refrigerate for at least 8 hours. Chop the rest of the Oreos and sprinkle them on top before serving.