Preheat the oven to 180C/355F/Gas 4. Grease and flour six dariole moulds.
For the sponge, beat the butter and sugar together in a bowl until pale and fluffy.
Crack in the eggs, then add the sugar, then the butter, beating thoroughly between additions. Mix in the lime juice, lime zest, toasted coconut, and flour until the mixture comes together to form a smooth batter. Add a splash of milk if the mixture is too dry.
Spoon the sponge mixture into the prepared dariole moulds, then place into the oven and bake for 20-25 minutes, or until the sponge is golden-brown and cooked through (the sponge should be springy to the touch). Remove from the oven and set aside to cool.
For the custard, whisk the egg yolks and sugar together in a bowl until pale and creamy, then sieve in the flour and mix well until smooth.
Place the coconut milk and vanilla pod and seeds into a heavy-based pan and slowly bring to the boil over a medium-low heat. Remove the pan from the heat as soon as the mixture reaches the boil, then remove and discard the vanilla pod. Pour the coconut milk mixture over the egg and sugar mixture, whisking continuously until well combined.
Pour the custard mixture back into a clean pan and cook over a medium heat, stirring frequently for 4-5 minutes, or until the custard thickens enough to coat the back of a wooden spoon.
To serve, turn the sponge puddings out from their moulds and place onto shallow serving bowls. Spoon the custard over the sponge puddings and serve with dollops of whipped cream.
