Put the corn syrup and sugar in a medium pot on around medium heat and stir frequently (though it doesn't need to be constantly) until the sugar is dissolved in the syrup.
Mix the peanut butter into the corn syrup/sugar mixture while it's still warm (but turn off the heat!) until the mixture is all smooth and creamy.
Pour the mixture into a large bowl containing the crisped rice cereal, and stir so all are coated. I always use a little more than a cup of each( corn syrup, sugar, PB) so that there is a higher peanut buttery ratio to krispy taste. Press the cereal mix into a greased 8x13 pan, or any size pan, and flatten.
Next, melt the the chocolate chips in a large microwaveable dish. Mix in a few slivers of margarine and a few drops of vanilla extract if you'd like. The original recipe calls for butterscotch chips, and this kind of helps to add a little different flavor than the thorough chocolate taste. You can also use less chocolate if you'd like, this makes a good sized chocolate layer.
Once the chocolate is melted and creamy, pour it over the cereal mixture in the pan and flatten. The chocolate will cool and dry in a few hours. Although,they are delicious when it's all melty- just a bit messy. Enjoy!
This recipe was adapted from the recipe on a Rice Krispie box.