If you start getting your caramel ingredients together when you've popped the base into the oven, it seems to time itself pretty well. Place all the ingredients into a saucepan over a low heat. Stir until the butter has melted and then cook for another 6-7 minutes. Don't expect it to thicken much or change in colour, just keep stirring it so that you don't burn the bottom!
When the base is ready, pull it out of the oven and pour the caramel over the top. Place the tin back into the oven for another 20 minutes. The caramel will darken and start to bubble...best thing ever!
Let the tin cool on the bench before popping it into the fridge. Leave it for a good couple of hours (I usually let it go overnight) to make sure that it is nice and cold.
While I do prefer to melt chocolate over a pot of boiling water, I use my Tupperware microwave jug for this recipe. Break the chocolate into pieces and drizzle the oil over the top. I put it in the microwave for 30 seconds at a time, stirring in between. This ensures that you have no disasters. When the chocolate is completely melted and is shiny and smooth, pour it over the chilled caramel. Tip and tilt the tin to allow the chocolate to spread evenly across the whole slice. Put it straight back into the fridge and leave until set. This usually only takes about 30 minutes.
Lift the slice out of the tin. To slice, I use a knife dipped into boiling water. This stops the chocolate breaking and makes you cuts clean and neat. Wipe the knife with a cloth in between to remove any melted chocolate. I start by chopping off the 'crispy' edges. (This is the favoured part in my house and hardly the scraps with all the dark, 'burnt' caramel!) Then you can cut the slice into pieces sized to your liking. Steal a piece at this point because you won't get a look in later on!