Preheat oven to 350 degrees F. Line a 9×13-inch baking dish or rimmed cookie sheet with parchment paper. Set aside.
Make the Crust:
Using a food processor, pulverize the Oreo cookies (or chocolate sandwich cookies) into a fine crumb. Add melted butter and sugar and pulse until combined. Press into the lined pan. Bake for 10 minutes. Allow to cool as you prepare the filling.
Make the filling:
Beat butter and sugars together at high speed with an electric mixer until light and creamy. Add eggs one at a time, making sure they are fully combined before adding the next one. Add the vanilla, reducing to medium speed and mix until blended. Add flour and salt, mixing until just blended. Stir in semisweet chocolate chips. Spread into prepared crust.
Bake for 35-40 minutes or until just set. The center will be a little bit gooey and will set as it cools. Remove from oven and transfer pan to a wire rack. Cool completely, about 1 hour.
Slice into bars and serve warm with ice cream and chocolate sauce. Enjoy!