Preheat the oven to 350 degrees.
In a large bowl, whisk together the flour, baking powder and salt.
In an electric mixer bowl, combine the sugar and softened butter on medium speed until light and fluffy. Add the coconut milk, eggs, vanilla, and sour cream. Mix until combine. Scrape the sides and bottom of the bowl using a rubber spatula. Add the flour mixture and mix on medium low until smooth. Remove the bowl from the mixer and gently fold in the toasted coconut.
Fill the lined cupcake tins 2/3 full with the batter. Bake for 24 minutes or until the top of the cupcake bounces back when lightly pressed. Cool for 5 minutes, then move to a wire rack to cool completely before frosting.
Combine the eggs, sugar, and salt in the bowl from an electric mixer. Place the bowl over a pan of simmering water. Whisk constantly, but gently to heat the mixture until it registers 160 degrees (warm to the touch and it will look thin and foamy). Remove the bowl from the heat and beat the mixture on medium high speed with the whisk attachment until light and cooled to room temperature. The bottom of the bowl should be cool to the touch. Reduce the speed to medium and add the butter one piece at a time. Once all the butter has been added, pour in the melted white chocolate, then the passion fruit puree. When incorporated, raise the speed to high and continue beating until light and fluffy. Scrape into a bowl, cover and refrigerate until you're ready to frost the cupcakes.
Frost the cupcakes with the buttercream using either a spatula or a pastry bag. The cupcakes can be kept in an airtight container in the refrigerator for up to 3 days. Garnish with the toasted coconut curls just before serving.
Jill's Wine Recommendation: 2009 Vietti Moscato D’Asti , which is a lightly sparkling, very delicately sweet dessert wine. The floral aromatics and refreshing acidity will work beautifully with the floral notes in the coconut and the tanginess of the passion fruit.