First, cook two complete sheets of puff pastry (or as much as you will need to line your dish or tray twice) until lightly golden, then when they are cooler, gently squash them flat with a chopping board or something, set aside.
Then in a big saucepan, Add custard powder ( a lot more than the packet says) at LEAST half a cup, if not more. I add about 3 tablespoons of sugar and a big splash of vanilla then add about 750 mls of Bonsoy
Stir and stir and stir, it should get so thick it is getting hard to stir.
If it’s not thickening enough, mix more custard powder with a little milk to make it runny and add it in, do that as much as you need to. The other option is to add a teaspoon of agar to thicken it up.
I use my lasagna dish, put one layer of pastry on the bottom, top with the warm custard and add the other pastry sheet on top.
Let it cool a little on the bench.
Once cooled add icing.
The icing is about two tablespoons of nuttelex, approx. two cups of icing sugar & a splash of vanilla, mix and add bonsoy until it gets nice.
Put icing on top and refrigerate until it’s all cool and set.