Step 1

Grease a 19cm x 29cm rectangular slice pan. Line base and 2 long sides with baking paper, extending paper 2cm above edges of pan.

Step 2

Place Mars bars and butter in a saucepan over low heat. Stir constantly, without boiling, for 5 minutes or until mixture is smooth. Remove from heat. Stir in rice bubbles. Press into prepared pan.

Step 3

Place chocolate in a microwave-safe bowl. Microwave on MEDIUM (50%) for 1 to 2 minutes, stirring every 30 seconds with a metal spoon, or until smooth.

Step 4

Spread chocolate evenly over top of slice. Refrigerate until firm. Using a warm knife, cut slice into squares. Serve.