Prepare the tray

• Line a baking tray with baking paper.
• Preheat the oven to 170 °C.

Make the caramel

• Melt the butter in a saucepan with the brown sugar and golden syrup.
• Bring to a gentle simmer and stir until smooth.

Coat the cornflakes

• Pour the cornflakes into a large bowl.
• Pour over the caramel and toss gently until evenly coated.

Bake the base

• Spread the coated cornflakes evenly on the lined tray.
• Bake until golden and set.

Add the chocolate

• Scatter the chopped dark chocolate over the hot cornflake base.
• Let it melt, then spread into an even layer.

Finish and set

• Sprinkle the flaky sea salt over the chocolate.
• Leave to cool completely, then break into shards.