Step 1

Grease and line the base and sides of a 20 x 30cm lamington pan, allowing the 2 long sides to overhang.

Step 2

Combine the butter and marshmallows in a medium saucepan over medium-low heat. Cook, stirring, for 5 minutes or until butter and marshmallows melt and mixture is smooth.

Step 3

Combine the rice bubbles and M&M’s in a large bowl. Pour over the marshmallow mixture and quickly stir to combine. Spoon mixture into the prepared pan, use the back of a spoon to smooth the surface. Place in the fridge for 2 hours to set. Cut into 3 x 10cm bars to serve.