For the biscuit base, sift flour and sugar into a bowl. Add coconut and butter and mix together with mixer. Press mixture firmly into baking sheet and bake 10-15 minutes, until golden brown.
To make the caramel, put the corn syrup, butter and condensed milk into a saucepan over low heat until butter is melted. Continue cooking for 7-10 minutes as the caramel thickens and darkens in color. Pour over prepared base and put back in oven for 20 minutes.
Remove from oven. Once it has cooled, prepare chocolate topping by melting the chocolate and oil together in a heatproof bowl set over a saucepan of simmering water, or in a microwave for one minute.
Pour the mixture over the caramel and smooth gently over the top. Sprinkle with cocoa powder. Allow to set before removing the whole slab from the baking sheet, then cut into slices.