Remove the After Eights you popped in the freezer earlier, and using a food processor or blender, blitz until they are fairly fine.
Take half of the chocolate crumbs and set to one side. Put the other half back in the freezer until later.
Add the milk to a bowl and enough icing sugar to make a very thick paste.
Stir in the crushed After Eights you had set to one side. Leave until it has thickened even more (the fondant needs to be fairly spreadable but not runny).
Spread the fondant over the cooled brownie, and place in the fridge to set for about an hour.
When ready, slowly melt the milk and dark chocolate together with the cream. You can either do this carefully in a microwave, or in a Bain Marie .
Slowly whisk or stir everything together, then pour over the top of the fondant.
Take the remaining After Eight crumbs out of the freezer, and sprinkle over the chocolate/cream mixture.
Allow time to set (a further hour) then slice into squares and enjoy (see note 4).