Rice bubbles - mars bar crunchy slice

Place baking paper onto a 19cmx29cm lamington pan.
Combine Mars Bars and butter in a large saucepan. Stir constantly over low heat without boiling until mixture is smooth. Then stir in rice bubbles. Press the mixture evenly into the pan.
Melt the chocolate with butter in the microwave with a microwave safe container. Heat on medium heat for 40 second, then stir a bit and repeat the process until the chocolate and butter are well mixed. Spread onto the slice and refrigerate until set before cutting.