This pie looks difficult but needs only about 45 minutes of active work – much of the time it takes to make is taken up with letting the dough rest in the fridge to firm up. Commercial puff pastry sheets vary in size and weight, so adapt the size (and shape) of the pie according to the brand of pastry you buy. The all-butter puff pastry I use (Waitrose) comes as two sheets that are about 28cm x 22cm (11 x 8½ in), so the brand you use should give you about the same total area of pastry. This...