Line a 28 x 18cm tin with baking paper. Make sure you leave plenty of paper hanging over the sides to help you remove the Mars Bar and Maltesers Slice once it has set.
Chop ONE Mars Bar into small pieces and set aside. Also roughly chop the Maltesers and set aside until needed.
Roughly chop four of the Mars Bars into small pieces and place them into a medium size saucepan. Add the butter and golden syrup and stir over a low heat until all of the ingredients have melted and combined.
Place the rice bubbles and extra chopped up Mars Bar in a separate bowl, and pour the melted over ingredients over them. Mix together until combined and pour into a slice tray. Use the back of a metal spoon to spread and press the slice into the tray.
Break the milk chocolate into squares and place in a microwave safe bowl and cook for 30 second spurts and stirring in between until melted.
Pour melted chocolaté over the slice and decorate with the chopped Maltesers. Place into the fridge for 4 hours to set.
Cut the set Mars Bar and Maltesers Slice into pieces and enjoy!