Scoop the pulp from the passionfruits into a small bowl. If you prefer a smooth curd, strain half the pulp through a sieve to remove some seeds, then recombine with the remaining pulp.

Set a heatproof bowl over a saucepan of gently simmering water, making sure the base of the bowl doesn't touch the water.

Add the passionfruit pulp, caster sugar, eggs, and lemon juice to the bowl. Whisk together to combine.

Stir continuously with a wooden spoon or heatproof spatula for 10–12 minutes, until the mixture thickens enough to coat the back of a spoon (about 75–176°F if using a thermometer).

Remove the bowl from the heat. Add the butter cubes a few at a time, stirring until each addition is fully melted and incorporated.

Pour the curd into a clean sterilised jar. It will thicken further as it cools.

Allow to cool to room temperature, then seal and refrigerate.