Line 20 x 30cm tin with some greaseproof paper. Melt butter in a saucepan until fully melted.
Add the marshmallows to the saucepan, turning down the heat to low. Keep stirring until it has melted fully.
Take the pan off the heat and add in the coco pops. Stir the coco pops in until fully incorporated then add about 5 bags of Maltesers into the mix.
Turn the malteser coco pop marshmallow mix into the tin and press it down until it covers the bottom of the tin.
Leave this mixture to cool for about an 1 hour. Then once cooled, melt the chocolate and pour over the coco pop layer until fully covered. Then add the rest of the coco pops to the top of it and leave to set.