1. Finely crush Oreos in a food processor. Alternatively, crush them with a rolling pin in a large zip-top bag. Mix with half a cup melted margarine, then press into a tart pan to form a crust. Freeze for 10 minutes to set.
2. Melt remaining half cup melted margarine, peanut butter, and confectioners’ sugar together and mix until smooth. Spread evenly over the crust and freeze for another 15 minutes.
3. Bring whipped topping to a boil, then pour over chocolate chips and mix until melted and smooth. Spread evenly over tart.
4. Let cool before slicing.