Lay the pastry out on a well-floured board, then sprinkle evenly with the tomatoes, parmesan, rosemary & plenty of pepper.
Carefully roll up both of the long sides of the pastry until they meet in the middle. Brush the area between the two parts of the roll with a little egg and push the two parts together so that they stick. Pop the whole roll into the fridge for at least half an hour (either pop it in on the board or if it won’t fit in the fridge carefully side onto something smaller like a baking tray.) Meanwhile, heat the oven to 200C/390F.
Remove from the fridge and slice into roughly 1cm-slices with a big sharp knife. Carefully place the slices on a baking tray lined with non-stick baking paper. Reshape them a little if necessary, then brush the tops with the egg.
Bake for 10 to 15 minutes until the palmiers are puffed and golden. Cool slightly on the tray, then serve while still warm!
It doesn’t really matter if your sheet of pastry is a little smaller or larger. Just adjust the amount of toppings you add accordingly.