Line your baking pan with parchment paper, letting the edges overhang for easy removal.
Spread the coconut flakes evenly on a baking sheet and toast in a preheated 180°C (350°F) oven for 5-7 minutes, stirring halfway through, until golden and fragrant.
While the coconut cools slightly, break the dark chocolate into small pieces and melt it gently in a heatproof bowl over a saucepan of simmering water, stirring until smooth and shiny.
In a mixing bowl, combine the toasted coconut, melted chocolate, honey or maple syrup, and butter. Mix well until everything is evenly coated and sticky.
Transfer the mixture into your prepared pan and press down firmly with a spatula or the back of a spoon to form an even layer. Chill in the fridge for about 15 minutes to set slightly.
Re-melt the remaining chocolate the same way and pour it over the chilled coconut layer, spreading evenly to cover the surface. Sprinkle a pinch of sea salt or additional toasted coconut on top if desired.
Place the pan back in the fridge and chill for at least 2 hours, or until the chocolate is glossy and fully set.
Once set, lift the entire block out of the pan using the parchment edges. Use a sharp knife to cut into even squares, wiping the knife between cuts for clean slices.
Serve immediately or store in an airtight container in the fridge for up to a week. These bars are best enjoyed when firm, with a crackly top and chewy coconut interior.