4 ounces (125g or one stick in the US) margarine
4 ounces (125g or one cup) self raising flour (All-purpose flour with baking powder)
3 ounces (75g or ½ cup) soft brown sugar
2½ ounces (60g or one third cup) crushed cornflakes
1 ounce (25g or one rounded table spoon) cocoa powder

1 pound (500g or 2½ cups) icing sugar (frosting)
2 teaspoons peppermint essence (extract)
5 tablespoons water
A few drops of green colouring (optional)
4 ounces (125g or one stick) chocolate (more if you like thicker chocolate!)

Preheat the oven to 325F/170C/Gas Mark 3 (less if a fan assisted oven). Melt the margarine in a non-stick pan and stir in the sugar, crushed cornflakes, cocoa and flour. Line a 9" (23 cm) square tin with baking parchment and spread the mixture into this. Bake in the pre-heated oven for 20 minutes.

Remove from the oven and allow to cool in the tin.

Mix the icing sugar (frosting), peppermint essence (extract) and optional colouring with water to create a thick paste and spread over the base. Allow this to set (preferably overnight).

Finally, spread with melted chocolate and allow to set. Cut into squares.