Bring the sugar and syrup to a boil and remove from heat. Add peanut butter and vanilla; stir until blended and smooth.
Pour peanut butter mixture over Rice Krispies and mix well. The cereal will incorporate, it may take some patience! Press into a buttered 9x13 pan. I usually put a little butter on my hands and pat evenly into pan.
Melt chips on 50 % power in your microwave in 1 minute intervals. Keep stirring to make sure the chips melt evenly and to avoid baking the chips. Once the chips are melted to a satiny texture spread over top of Rice Krispie mixture. Let cool. Cover and keep in refrigerator if weather is warm.
These are sweet, when cutting keep the squares small!