These were THE dessert of elementary and middle school. As I've gotten older, I've also learned they were ubiquitious and not just limited to my elementary and middle school. It makes me think there's a lunch lady recipe book all schools received.
Put Butter and Peanut Butter in a large microwave-safe bowl. Microwave until butter and peanut butter are melted in 30-second increments, stirring after each 30 seconds.
When melted remove and add the remaining sugar and vanilla. Stir together until a large ball of dough forms and starts to pull away from the sides of the bowl.
Remove from bowl and spread into a 9x13 pan.
Pour chocolate chips into another microwave-safe bowl and microwave at 30-second intervals, stirring after each, until completely melted. Spoon over top of peanut butter mixture and spread evenly.
Allow to cool completely by placing in the refrigerator for about an hour.