It's called an Afghan biscuit, traditional in New Zealand and popularised by the influential Noel Edmonds Cookery Book. Nobody knows why they are called Afghan biscuits or why Noel hasn't published his book in the UK. It contains no raising agent and not much sugar, giving it a soft dense texture, just on the right side of seeming slightly stale like a Tunnock's caramel wafer or a Twirl chocolate bar.
Yesterday out of nowhere I craved the same biscuit, googled the recipe & baked some.
Here is the recipe:
makes 6 large biscuits or 12 small ones
For the biscuits:
200g softened unsalted butter (or dairy free margarine if you want a vegan version)
75g caster sugar
175g plain flour
25g cocoa powder
For the topping:
60g double cream (or coconut milk if you want a vegan version)
120g dark chocolate
Preheat the oven to 180 degrees C and grease an oven tray
Cream the butter and sugar, then add the flour and cocoa.
Add the cornflakes & try not to crush them too much
Place spoonfuls of the mix on the oven try and bake for about 15 minutes
Leave to cool
To make the topping, bring the cream to boiling point, them remove from heat.
Add the chocolate and stir.
Spoon some chocolate mix into each biscuit and place a whole walnut on top.