These are not the good pieces. I just like them because they are all curvy and shiny – they’re the pieces that were on the edges of the dish.
Prepare a dish by giving it a quick blast with spray oil. I use a little ceramic dish about 20x12cm – err on the smaller side because if the layer is thick you can just cut it into smaller squares. I also put a strip of baking paper in the dish just to be sure I can get the bugger out if it goes awry.
Melt 125g butter (not margarine, by all that is holy, do not try to turn this into a health food), throw in a cup of brown sugar, two tablespoons of golden syrup and a tin of condensed milk. I’m going to assume you know not to throw in the actual tin.
Stir over a medium heat until it boils, then continue stirring for about twice as long as you think is humanly possible. Seriously, you cannot do this quickly. Half an hour or more. You have to stir constantly while it gets darker and thicker, until it is as dark as the picture above, and so thick it starts coming away from the pan. Not coming away like dough that comes together, much more subtle than that. But you can see a change in consistency that means it kind of lifts away as you stir. It has to be boiling but not boiling fast. You want the temperature to rise as slowly as you can manage it, because otherwise it will burn on the bottom before it caramelizes.
Now tip it into the dish really quickly and with minimal scraping of the saucepan. Don’t even scrape it this much:
The stuff you scrape is a source of crystallization which is what you don’t want. What’s left in the pot is really useful for torturing children. “No. It’s too hot. It’s still too hot. Oh, now it’s too stuck to the pan. Sorry kids.” but don’t worry, they’ll manage to get some off. The rest just soaks off in water, no drama.
Let it set. Hot-rinse-and-dry your knife regularly while cutting it up.