Pre-heat oven to 180C.
Take half a thing of shortbread and squidge it into a tin about 20 by 30cm: a yokki tin. Put it into the oven and bake for 30 minutes. Cool until cold — overnight is good. You really don’t want to put the fudge on while it’s still warm, it spoils the texture.
For the fudge you need an electric cooker, a heavy-bottomed pan and a good wooden spatula.
Put a tin of sweetened condensed milk, a tablespoon of golden syrup, 3 ounces of sugar and 2 ounces of butter (marge) into the heavy bottomed pan. Turn the heat on low. Stir until the butter has dissolved. Turn the heat up and bring to the boil. When it is boiling, stir constantly, always scraping the bottom and the sides for 5-6 minutes, or as long as it takes to sing Matty Groves or listen to A New World. (You’ll burn it if you try to use My Brother, My Enemy. Just saying.) What you’re technically doing is called “getting it to the soft-ball stage” and there are weird and arcane ways of testing it with glasses of water and sugar thermometers, but Matty Groves or A New World works just as well.
Take the fudge off the heat and beat hard for a little while. Then pour it evenly over the shortbread, making sure it covers it properly.
Then take a saucepan with a glass lid and put some water in it. Bring the water to the boil. Put the glass lid on the pan upside-down, and put 200 grammes (8 ounces,) of chocolate on the lid. Turn the water down to a simmer, and wait for the chocolate to melt. When it has melted, spoon it over the fudge. You don’t have to wait for the fudge to be cold. Spread it evenly.
When completely cold, cut into squares.
1) It’s possible to use two different kinds of chocolate, for instance Cadbury’s Dairy Milk on one half and Lindt 70% or Lindt Fleur de Sel on the other half. I do this all the time. You need to use two pans for melting the chocolate, obviously.
2) It is possible to make this on a gas cooker, but you have to catalyse the fudge. The thing is that electric rings are constantly on the point of caramelising everything anyway, so it does it automatically. But a gas ring, superior in every other way, won’t do this, so you have to do it yourself. Take a big tablespoon and put a teaspoon of sugar in it. Turn a ring up full, and hold the tablespoon on the flame until the sugar melts and burns. Then pour that into the fudge and keep stirring.
3) People have asked about the name. It’s an old Leicestershire name told to me by my friend Paula, whose recipe this originally was. The spelling is hers too. Many people call it “millionaire’s shortbread” and “chocolate caramel shortbread” and so on, but many people who have eaten it with me now call it yokki.