Chop the milk chocolate into small pieces and measure out the peanut butter. Set both ingredients aside until needed.
In a medium saucepan combine the sugar, cornflour and cocoa. Add the milk and cream and whisk together over a medium high heat until the mixture starts to bubble and come to the boil.
Cook for one minute before removing from the heat, add the peanut butter and chocolate and stir to combine.
Divide amongst 4 small bowls and allow it to cool slightly.