Passion curd

Cut up the passion fruits and cut out the pulp. Place in a pan together with the juice of one lemon. Heat for about 1 minute while stirring. Pour through a fine-meshed sieve to remove the passion fruit seeds. Use a spoon to press out as much of the juice as possible.
Pour the passion fruit juice into a pan and whisk in the egg yolks, the whole egg and the jam sugar. Bring to boil while stirring constantly for about 5 minutes. Remove from the heat and add the butter a little at a time.
Pour the curd into a thoroughly-cleaned jar. Seal and store in a cool, dark place.