Begin by cutting the passion fruits in half and using a spoon to scrape the seeds into a saucepan.
Heat these over a medium heat for about 5 minutes to help the seeds release their juices. Then remove from the heat and strain through a fine mesh sieve, scraping the seeds against the sieve to press the juices out into a bowl.
Return the juice to the saucepan and add the sugar, egg and yolk. Whisk together while heating over a medium heat for about 10 minutes until thickened enough to coat the back of a spoon.
Remove from the heat and decant into a heatproof bowl or jar to cool completely before serving.
Twelve passion fruits should produce between ½-¾ cup of juice once strained through the sieve. You can replace the fresh passion fruits with the equivalent amount of fresh passion fruit juice. Do not use juice from concentrate. See the blog post for more tips, tricks and process photos.