Add the Rice Krispies, and fold in until completely coated in chocolate.
Pour into the prepared pan and spread out evenly. Refrigerate for 1 - 2 hours until set. Slice into bars and serve cold or at room temperature.
These bars can be stored in an airtight container at room temperature or in the fridge for up to 3 weeks. They also freeze well for up to 2 months. Thaw overnight in the fridge before serving.
The calories are an estimate only.
I cut my bars into 8 long bars for the photos, which would be 370 calories each.