This recipe is by Shaun Clouston, Logan Brown (Wellington), from The Great New Zealand Baking Book (published by Thom Productions and PQ Blackwell, $49.95).
Heat oven to 160C fan-bake or 180C regular. Grease and line a baking tray.
Cream butter and sugars together until fluffy. Sift flour and cocoa together and add to creamed mixture. Stir in cornflakes.
Place 24 heaped teaspoonfuls of mixture on the tray and bake for 10–12 minutes. Cool on a wire rack.
Place chocolate in a medium-sized bowl. Heat sugar, without stirring, in a medium-to-large pot on a medium heat until it becomes a light golden caramel colour. Slowly pour cream in and whisk until smooth — be careful, as the sugar can spit as you pour it in. Pour caramel over chocolate and whisk until smooth, then whisk in salt and milk. Set aside to cool.
Once everything is cooled, sandwich biscuits together with milk caramel and roll the sides in chopped walnuts.