Exotic and enticing, these whoopie pies are filled with mango pieces and topped with passion fruit. They are also good with other tropical fruits, such as papaya and star fruit (carambola).
Preheat the oven to 180°C/350°F/Gas 4. Line two baking trays with baking parchment or silicone mats. For the cakes, whisk the butter, sugar and vanilla seeds until fluffy. Whisk in the egg.
In a separate bowl, sift the flour with the bicarbonate of sod