Line a baking tray with parchment paper, or a silicone mat. Set aside.
Add the chocolate and peanut butter to a microwave-safe bowl, and heat in 30 second intervals, stirring after each one, until melted and smooth.
Add the Cornflakes, and fold in until completely coated in chocolate.
Drop spoonfuls of the Cornflake mixture onto the prepared baking tray, and refrigerate until completely set - about 30 minutes.
These cookies can be stored in an airtight container 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.