Line the base and sides of a slice tin with baking paper.
Finely crush the Chocolate Ripple Biscuits. You can use a food processor or the end of a rolling pin if you are like me!
Roughly crush 1 cup of Maltesers.
Dice the Mars Bars into small pieces.
In a small saucepan over a low heat, melt the butter and condensed milk, stirring until combined.
Add the roughly crushed Maltesers and Mars Bars to the crushed biscuits and stir through. Then add the melted butter and condensed milk and stir until combined - it will be very sticky!
Pour the mixture into the slice tin and flatten with the back of a metal spoon. Pop it in the fridge for approximately an hour until it has completely cooled.
Melt both of the blocks of chocolate and add 1 teaspoon of vegetable oil to the melted mixture, making sure you stir it in.
Pour the melted chocolate over the cooled slice and then decorate with remaining Maltesers.
Put the slice back into the fridge and cut into pieces before it has completely set.