Cut the butter into pieces. Chop the chocolate with a serrated knife. Cut the passion fruits in half and scoop out the flesh with a small spoon. Sieve to give 250 g of juice. Weigh the juice and bring it to the boil. Melt the chocolate in a bain-marie. Pour the hot juice into the chocolate in three stages. Once the mixture reaches 60 °C, incorporate the pieces of butter a little at a time. Mix until the ganache is smooth and mix with a stick blender. Pour into a gratin dish. Cover with cling film, ensuring it is in contact with the surface. Set aside in the refrigerator until it has a creamy consistency.

NB: if the ganache splits when the passion fruit juice is added, that is quite normal. It is because the fat molecules in the chocolate separate. Simply continue mixing as instructed in the recipe, and you will end up with a beautiful shiny, unctuous ganache.

Sift together the icing sugar and ground almonds. Mix the colours into the first quantity of whites. Incorporate them into the icing sugar-ground almond preparation without mixing.

Boil the water and sugar until the temperature reaches 118 °C. Once the syrup gets to 115 °C, simultaneously start whisking the second quantity of egg white to form soft peaks.

Pour the cooked sugar at 118 °C into the whisked whites. Whisk and leave to cool to 50 °C before folding them into the icing sugar-ground almond preparation; mix everything together, removing the air from the paste. Pour it into a piping bag with a no. 11 plain nozzle.

Pipe the paste into circles approximately 3.5 cm in diameter, spacing them 2 cm apart on baking trays lined with baking parchment. Tap the trays on a work surface covered with a tea towel. Use a sieve to dust them with a light coating of cocoa powder. Leave the shells to harden (dry) for at least 30 minutes at room temperature.

Preheat the fan oven to 180 °C (Gas mark 4). Slide the trays into the oven. Bake for 12 minutes, opening the oven door briefly on two occasions. On taking them out of the oven, slide the shells onto the work surface and allow to cool.

Pour the ganache into a piping bag with a no. 11 plain nozzle. Turn over half the passion fruit macaron biscuit shells onto a sheet of baking parchment. Fill them generously with ganache. Cover them with the other shells. Store the macarons in the refrigerator for 24 hours. Remove them from the refrigerator 2 hours before serving.