Preheat the oven to 170°C. Grease and line a square cake pan. Process butter and sugar in a processor for 2 minutes until light.
Add 1 teaspoon vanilla. Add egg replacer, flour,and milk, pulsing to combine. Pour into pan and bake for 55-60 minutes until a skewer inserted in center comes out clean.

Cool for 5 minutes, then turn onto a rack to cool completely. Then stir chocolate, cream and remaining vanilla in a heatproof bowl over simmering water until smooth.
Chill for 20 minutes to thicken. Spread this icing over the cake, then sprinkle top and sides with coconut and serve.