Dessert

Grease and line a 20 x 20cm baking tin with parchment paper
Melt the chopped Mars Bars and butter in a heatproof bowl over a pan of barely simmering water, whisk until smooth
Pour the melted mixture over the Rice Krispies and mix until evenly combined
Press the mixture evenly into the prepared baking tin and set aside
Melt the milk chocolate in the microwave or over a pan of barely simmering water
Spread the melted chocolate over the rice krispie mixture and leave to set in a cool place
Once set slice into squares and serve