Place a sieve over a clean bowl and set on the counter close to the stove. You will need this for the curd as soon as it reaches the desired temperature in step 4.
Add the pineapple puree to a small saucepan and bring to a rapid simmer over medium-high heat, until reduced to ¼ cup. Pour into a measuring cup to check that it has been reduced enough, if not return to pot and heat some more. This took me just over 5 minutes (original recipe indicated 2-4 minutes). Pour into a measuring cup and combine with the zest and lemon juice. Set aside to cool to room temperature.
In a separate bowl, whisk together the egg yolks and sugar. Pour the juice mixture into the egg mixture in a steady stream, while whisking. By adding the warm liquid slowly to the eggs, you are tempering the eggs to avoid ending up with scrambled eggs.
Pour the juice and egg mixture back into the saucepan and set it over medium heat. Gently stir the mixture constantly until it thickens enough to coat the back of a spoon, or reaches 180ºF.
Remove from heat and pour through the sieve into the prepared bowl. This removes any chunky bits of eggs and zest. If you want the finished curd to have the zest, add fresh zest to the strained curd. While still warm, stir in the butter, salt, vanilla beans.
Allow to cool, then transfer to an airtight jar. The curd will keep in the refrigerator for about a week (but I guarantee you it will not stick around for that long).
Assemble the trifle:
Break cake into chunks or cut into shape/size that fits the dish(es) being used. Alternate layers of cake, curd and mousse and top with pieces of cake, fruit or curd. Enjoy!