Grease and line with baking paper a 25cm x 16cm x 2 1/2cm (10in x 6in x 1in) baking tray. Make sure the paper has a 2cm over hang

Melt Copha in microwave on high or in saucepan until fully melted. Using a food processor, crush biscuits until they resemble fine breadcrumbs

Mix melted Copha and biscuit crumbs together. Then press biscuit mix into baking tray firmly, using the back of a spoon if necessary. Put in the fridge to set for 10 to 15 minutes

Make the White Chocolate Crackle layer as follows:

In a large bowl, combine together white chocolate and Copha. Place bowl over a pot of lightly simmering water. Stir occasionally until melted. Remove from heat

Add icing sugar, rice bubbles, milk powder and coconut to the bowl. Stir to combine

Pour crackle mix over the biscuit base and spread evenly. Put back in the fridge to set

In a large bowl combine dark chocolate and Copha. Place over a pot of lightly simmering water. Stir occasionally until melted. Remove from heat

Add icing sugar, rice bubbles, cocoa powder and coconut to the bowl. Stir to combine. Pour dark chocolate crackle mix over white chocolate layer and biscuit base and spread evenly. Put back in the fridge to set