Line a 20cm x 20cm square cake tin with baking paper, making sure you leave plenty hanging over the edges to help you remove the slice once it’s set.
Place BOTH packs of the plain biscuits into your Thermomix Bowl and crush for 4 seconds on speed 4. Scrape down the sides of your bowl and mix for a further 5 seconds, speed 4 until all the biscuits are finely crushed - you will need to use your spatula to push the biscuits down into the bowl. Set aside until needed.
Pour the condensed milk into your Thermomix Bowl and add the butter (3cm pieces) and cocoa. Cook for 2 minutes on 60 degrees speed 1 or until the butter has completely melted.
Add the biscuits and shredded coconut to your Thermomix Bowl and mix for 10 seconds on speed 4 or until the mixture has combined.
Pour the mixture into your prepared slice tin and flatten the surface with the back of a metal spoon.
Clean your Thermomix Bowl and make sure it’s completely DRY before adding the chocolate pieces. Cook for 2 minutes on 50 degrees speed 3 or until the chocolate has completely melted.
Pour melted chocolate over the top of your slice and place it in the fridge for 4 hours or until set.
This recipe can be stored in the fridge for up to 7 days.