To make the chocolate sauce, whisk together the cocoa powder, golden syrup and coconut milk in a small saucepan, bring up to a simmer and cook for a minute, whisking constantly. Remove from the heat and stir in the vanilla extract, then add the chocolate and stir until smooth. Set aside.
Preheat the oven to 180C/350F/gas mark 4. Spread the desiccated coconut out on a baking tray and toast in the oven for about 10 minutes, stirring regularly, until golden. Place 80g (2.75oz) of the toasted coconut in a food processor or blender with the sugar and set the rest aside. Blitz until the coconut has formed a rough powder.
Tip the powdered coconut into a large bowl and add the flour, baking powder, bicarb and salt, mix until it is mostly free of lumps then add the egg and gradually whisk in both milks until the batter is smooth, it should be quite thick but add a little more skimmed milk if needed.
Heat a little bit of butter or coconut oil in a frying pan over a medium/low heat, dollop a couple of spoonfuls of the batter in the pan (I use 2tbsp per pancake) and sprinkle a bit of the reserved toasted coconut over the top. Cook for a couple of minutes until set around the edges and bubbles have formed in the top of the pancake, flip it over and cook for a couple more minutes until cooked through. Repeat until you have used all of the batter.
Re-warm the chocolate sauce and serve the pancakes topped with the sliced banana, a sprinkling of toasted coconut and a generous helping of chocolate sauce.