Pre-heat oven to 160C (140C fan-forced). Line 12 x 1/3 cup capacity muffin pans with paper cases. Place butter, sugar, cocoa, milk and bi-carb in a saucepan and heat over a low flame until butter is melted. Allow to cool.
Whisk the eggs into chocolate mixture, until well combined. Fold in the flour and coconut, mixing well. Spoon mixture between paper cases and bake for 20-22 minutes. Allow to cool.
For the nests, place chocolate in a heatproof bowl over a saucepan of simmering water. Stirring until melted. Add coconut and mix well. Place spoonfuls onto a lined oven tray and using the back of the spoon, make an indent in the middle. Refrigerate until chilled.
To finish, place a coconut nest on top of each cake and fill with little Easter eggs.