1. In a bowl, thoroughly mix together graham cracker crumbs, powdered sugar, peanut butter, and margarine.
2. Spread the mixture onto the bottom of a 9x13" pan. In a small microwave-safe bowl, combine the chocolate chips and oil, and microwave for 30 seconds.
3. Mix the chocolate and continue to microwave at 10 second intervals until the chocolate is creamy and spreadable.
4. Spread the chocolate over the peanut butter mixture and place the pan into the refrigerator until the chocolate has hardened.
Source of recipe: My sister made these a while back, and they are amazing!