Whisk dry ingredients together in a medium pot.
Pour in about ½ cup cream into the pot and whisk with the dry ingredients. Combining a little liquid with the dry ingredients first will help prevent clumping.
Pour in the rest of the cream and the pineapple juice and whisk to fully combine.
Whisk in the egg yolks.
Turn on the heat to just below medium and cook, whisking constantly, for about 7-9 minutes, or until the custard starts to thicken.
Cook the custard for another 30 seconds to a minute so that it starts to set. Be careful; once it starts to thicken, things move quickly and it can easily thicken too much too fast.
Remove from the heat and pour the custard through a fine mesh strainer.
Whisk in the butter, stirring for a couple of minutes to make sure it fully incorporates and emulsifies. Rushing this or undermixing the butter may cause a grainier texture.
At this point, you can chill the custard in the fridge for 3-4 hours until it sets up even more, or you can eat it as is.