Preheat the oven to 350 and line a 9x5 inch loaf pan with nonstick foil.
In a large bowl mix the flour, cocoa powder, sugar, coconut and cornflakes together.
In another bowl, heat the dark chocolate and butter in the microwave on high for 30 seconds. Stir and repeat until chocolate is melted and smooth.
Mix the melted chocolate and butter mixture into the dry ingredients. Press into the loaf pan.
Bake for 18-20 minutes, then remove from oven and let cool completely.
Once completely cool, melt the topping ingredients together in a microwave and spread on top of the cornflake slice. Sprinkle over the cornflakes and leave to set before cutting into slices.