Pre-heat oven to 180°C (160°C fan-forced). Line the base and sides of a 20cm cake pan with baking paper.
For the cake, place butter and sugar in the bowl of an electric mixer. Beat until creamy. Add eggs one at a time, mixing well between additions. Fold in coconut, flour and baking powder, alternately with the milk. Continue mixing until the batter is smooth. Pour into the prepared pan and bake for 45 minutes. Remove to a wire rack to cool completely.
For the passionfruit curd, place sugar and eggs in a microwave proof bowl, whisk until pale and creamy. Add butter, whisking in well. Microwave on high for 1 minute, stir and then continue in 30 second bursts, whisking each time until mixture is thick and glossy. Stir in passionfruit and lime rind. This process may take 3-4 minutes. Set aside, pressing cling wrap onto the surface to prevent a skin forming and refrigerate until cold.
Whip cream in the bowl of an electric mixer until soft peaks form, add yoghurt and continue beating until firm peaks. Fold the chilled passionfruit curd through the cream (remove lime rind and discard).
For assembly of the trifle, cut the cake into two layers, cutting through horizontally. Place one layer in the base of a large trifle dish, top with a layer of diced mangoes, raspberries and pulp of one passionfruit. Then dollop over half of the cream mixture. Repeat layering, finishing with cream on top. Cover and refrigerate for at least 4 hours, or leave overnight. When serving, top with passionfruit, pineapple and mint.