Preheat oven to 180°C Grease twenty 1 1/2 tbs (30ml) capacity mini-muffin pans.
Combine butter and sugar in a bowl, stirring with a wooden spoon, until pale and creamy. Add flour and coconut and stir until well combined. Spoon 1 1/2 teaspoonfuls of mixture into the base of each pan, pressing down evenly with your fingers. Bake in preheated oven for 8-10 minutes or until lightly golden. Remove from oven and reduce oven temperature to 160°C
To make the caramel filling, combine the condensed milk, golden syrup and butter in a small saucepan over medium-low heat and cook, stirring, for 1-2 minutes or until mixture is smooth. Pour evenly among the muffin pans. Bake for 5-7 minutes or until golden brown and filling sets. Remove from oven and set aside to cool. Use a small, sharp knife to carefully run around the edge of each pan to remove caramel cups. Transfer to a wire rack.
Place chocolate in a heatproof bowl over a saucepan of simmering water (don't let the base of the bowl touch the water). Stir until chocolate melts. Remove from heat. Pour into a plastic bag and cut off a corner. Pipe melted chocolate over each caramel cup. Allow 30 minutes to set. Store in an airtight container for up to 3 days.