(passionfruit) curd tart

Put  everything but the butter in a double boiler (in the case of this  passionfruit curd there is no zest, but do add like a lemon wedge worth  of lemon juice). Whisk until thickened - it’ll take a while. It needs to  generously coat the back of a spoon. Strain over the butter and mix til  the butter is melted. For a tart, it’s also advisable to use gelatin to make it hold up better when you cut it. I’m lazy so I didn’t. Pro-tip:  If you’re using juice, always use 100% unsweetened juice. Before making  the curd, put 12 oz. of the juice in a sauce pan and reduce to 6 oz (I  made a cranberry curd tart for Thanksgiving with this method). With  this, I used purée, which is already potent enough without reducing. Crust is digestive biscuit with lime zest, allspice, and ginger (falernum), passionfruit curd filling, topped with almond meringue (orgeat)