1 pack puff pastry
few spoons of caster sugar
Sprinkle a largeish board with some of the sugar. Roll out the pastry on the board (or cheat and use ready-rolled pastry). If you've got a 500g pack, then it may be easier to make the palmiers in two batches. Sprinkle the pastry with some more sugar, then fold the long sides into the middle. Add yet more sugar, and fold it in half again lengthways. Wrap in clingfilm, and stick in the fridge for half an hour.
Heat the oven to 200°C (gas mark 7, fan 180°C). Slice the pastry roll up into 1cm-wide strips, and place them edge side down on a baking tray (lined with baking paper), allowing space for them to expand sideways (about an inch each side). I managed to fit 12 or so on a tray. Put the tray in the oven for 8-10 minutes, then turn them over as they're starting to become golden-brown and give the other side 6-8 minutes.
With a fan oven, you'll probably want to give them 8 minutes one side and 6 the other, and watch them like a hawk as they will burn when your back is turned. With a non-fan or gas oven, they're less likely to burn and are more likely to need 10 minutes a side. They should look golden brown when done. If they taste chewy, then they could do with a bit longer; likewise, if they are what in our house are known as a "Nik special" and consist mainly of carbon, then you've probably cooked them for too long.
Don't do what I did either, which was to push the baking tray right to the back of a gas oven, then wonder what was causing the smell of fireworks and the smoke. Baking paper is not fireproof, and I managed a charred hole in the paper (as well as a blackened palmier or two which got eaten by Nik).