Preheat oven to 180C
Grease & line 20x20cm tin
In a big bowl, use your hands to mix the butter sugar and flour to form a slightly crumbly dough
Press firmly into tin, and smooth the top with your palms
Bake at 180C for 20 mins
Pop in fridge to cool
Meanwhile, add all caramel ingredients to a big saucepan
Over a low heat, stir continuously until the sugar has melted (no grainy texture when tested with a spoon)
Bring to the boil, then simmer for 6-8 minutes, stirring continuously
The caramel will turn a golden brown & start to thicken. (It’s ready when you place a drop on a plate/saucer and it sets before dripping off)
Leave to cool for 5 minutes, then stir and pour over the chilled base
Return to the fridge to set
After an hour, melt the chocolate in a microwave safe bowl
Add oil & stir until smooth
Pour over the caramel & smooth with a spoon
Return to the fridge to set
Once set, remove from the fridge 10 mins before slicing
