Melt the honey and salt in a pan over a medium heat, then slowly add the sugar and leave for a few minutes to melt and lightly caramelise.
Heat the cream in another pan to just about boiling.
When the sugar has reached a golden caramel colour, add the cream, standing well back in case of spitting. Stir vigourously and continue to cook for a few minutes until the caramel is thick and golden but still liquid. Remove from the heat and leave to cool.
Melt the butter and chocolate in a large pan over low heat.
Remove from the heat, add the sugar and stir. Beat in the eggs one by one, then sift in the dry ingredients.
Stir until just combined, then pour the mixture into a 20 cm square mould (line as appropriate).
Spoon the cooled caramel over the top, then swirl the mixture around to create a ripple effect - it will look very liquid at this point, but don't worry.
Bake at 180℃ (350℉, Gas 4) for 25 minutes until well risen with only a slight wobble. Scatter a large pinch of Cornish sea salt flakes over the top.
Please note: calories and other nutritional information are per serving. They're approximate and will depend on exact ingredients used.