Got to be 'Plot Toffee'.
It's good for keeping kids quite, great at removing loose teeth, lasts for hours, easy to make, everyone loves it on account of thay can't say they don't once in it's in there, can be eaten like a fudge, can be eaten hard enough to crack your jaw, can be white, brown, amber or black, it sticks bangers back to back, melted it seals greenhouse window and best of all it will start the bonfire off on a wet night.
Beat that for the worlds greatest sweety.......... :P
