Salted Caramel Tiffin

When I was growing up, my Mum used to make us Polish cake. It was this beautifully simple combination of mostly biscuits and chocolate that didn't require baking. I remember finding it so hard to resist the temptation to sneak a piece every time I opened the fridge. But I don't think I ever did, because I thought it would have been too obvious. We all loved this chocolatey treat that my Mum would cut up into tiny mouthfuls (unlike the enormous slabs pictured above!). When I moved away from home to go to university, this was one of the recipes that I had to take with me. I remember making it for my housemates, and two memorable things happened:
1) My friend's asked what was Polish about this cake, and I had no idea. It was one of those occasions where I realised that something that seemed completely normal to me because I had grown up with it, seemed odd to other people. 
2) I dropped my housemate's camera into the melted chocolate. Miraculously, it still worked.

I still don't know why it is called Polish cake, so for the sake of avoiding confusion, I'm calling it tiffin. I honestly can't remember the last time I made this recipe. It has been so long that I had thrown out the recipe book where I had carefully written it, so for future reference, here's the recipe, with the addition of salted caramel. My mother never added salted caramel, but I have developed a bit of a fondness for the sweet & salty goodness this year, and I thought it would be the perfect addition to this recipe.

ingredients for the tiffin
110g margerine or unsalted butter
2 rounded dessertspoons of drinking chocolate (if you use cocoa, it makes it very rich)
225g digestive biscuits (graham crackers for American readers)
30ml golden syrup
165g dark, milk or white chocolate
about a tsp of coarse sea salt

ingredients for the salted caramel
40ml double cream
15g unsalted butter
40g golden syrup (Karo syrup or King syrup in the US would work fine)
60g caster sugar
vanilla extract (optional)

method for the tiffin
1) Grease and line a 2lb / 1kg loaf tin or a 7" round cake tin.
2) In a saucepan, melt the butter or margerine, along with the drinking chocolate and golden syrup.
3) Crush up the biscuits - I put them in a freezer bag then bash the bag a bit with a rolling pin. Don't go too over the top with you bashing, otherwise you'll end up with lots of fine crumbs, rather than nice big chunks of biscuit.
4) Stir in the biscuits to the melted butter mixture, then press into your prepared tin. Place in the fridge to chill while you prepare the salted caramel. If you're omitting the caramel, just pour over your melted chocolate, then place in the fridge to set.
5) Melt the chocolate in a heatproof bowl over a pan of simmering water, or in a microwave.
method for the salted caramel
1) Measure the cream into a small frying pan / skillet, along with 7g of the butter and a good pinch of sea salt. Whisk gently over a low heat for a couple of minutes until the cream starts to thicken and bubble around the edges. Remove from the heat and stir in a small amount of vanilla extract (about 1/4 tsp). 
2) In a small saucepan, heat the golden syrup and the sugar over a medium heat. Don't stir it with any utensils, just swirl the pan every now and then to help the sugar dissolve. Allow the mixture to bubble for 3-4 minutes until it turns a slightly deeper golden colour and smells like caramel. 
3) Remove from the heat then stir the cream in with the caramel mixture with a heatproof rubber spatula, then stir in the last 8g of unsalted butter. There's no need to put the heat back on as the residual heat will melt the butter quickly.
4) Add another pinch of salt to the caramel, then pour over the tiffin. Allow to chill in the fridge for 15-20 minutes before pouring on the melted chocolate. 

Baking notes on the salted caramel
If you allow the salted caramel to chill in the fridge, the consistency changes significantly. After 15 - 20 minutes, it will become stretchy and malleable, as opposed to pouring consistency, which is perfect for using in brownies. If it's left for longer, it will harden further. It can be kept in the fridge for up to a week. It doesn't go off after this time, but sugar crystals start to form, which doesn't enhance the consistency!