First, preheat your oven to 180C/160C fan/Gas 4. Line a square brownie tin (7 inch square) with some baking paper (non-stick greaseproof) – just shove it in there.
Make the shortbread – first soften the butter in a microwave if it’s not already soft, then just mix it until it comes together with the flour and sugar. Use your hands to work it until it mops up all the crumbs – you don’t need to add any extra liquid. You can use a food processor here.
Press this out flat with your hands so that it fills your lined tin, then bake for 10-15 minutes or until it is just blushing golden brown at the edges.
Whilst it’s baking, you can start the caramel. Weigh all the ingredients together into a saucepan and place on a medium-high heat. Keep stirring gently. When it is bubbling (be VERY careful as it can cause terrible burns), keep an eye on it – you should start to see little slivers of brown where it has stuck on the bottom of the pan.
When you see these bits, turn the heat down to low-medium and (still stirring) simmer gently until it is a colour that you like. I like a deep, golden brown. Usually, whilst you’re doing this, your biscuit base will need to come out the oven.
When ready, pour your caramel onto your biscuit base and spread over the top with a knife. To even out the surface, pick your tin up and drop it onto your countertop. Leave this to cool for at least an hour (up to overnight) before doing the chocolate
Melt the chocolate in a microwave, by zapping it for 15 seconds then stirring it vigorously, and repeating until it is melted. You want it to be JUST melted. Pour it onto your cooled caramel surface and spread with a knife. Again, to even out, pick it up and drop it onto your countertop. Leave to set (another hour, NOT in the fridge), before slicing into slices. Heat up your knife with water from the kettle to make slicing easier.
Caramels can be tricky – even soft, fudgy ones like this one. If you’ve had trouble before or are lacking confidence, add a squeeze of lemon juice into your caramel ingredients. It won’t stop it burning, but will stop the dreaded “crystallisation”.