Made this today with left over puff pastry in fridge.
Used large Pyrex dish. Custard slightly wider than pastry. It cut ok.
Used 180g sugar. Still a bit sweet for us.
Ran out of custard powder so made up difference with more cornflour. Sprinkled sliced almonds on top of glacé icing.
Here is pic, in fridge with cling film on top. I think it would make 18 slices.