Line 2 large baking sheets with nonstick baking paper. Put the hazelnuts in a large, dry frying pan and toast over a medium-low heat for 4–5 minutes, shaking frequently, until lightly toasted. Tip into a food processor with the spices and blend until finely chopped. Place the sugar in a bowl and stir in the nuts.
Unroll the pastry on a clean surface and brush lightly with some of the melted butter. Sprinkle over the nut mixture, then roll the long sides of the pastry into the centre. Cut into 30–40 x 1 cm (1/2 inch) slices and place on the prepared baking sheets. Brush with the remaining butter.
Bake in a preheated oven, 220°C (425°F), Gas Mark 7, for 10 minutes, then remove from the oven and turn the palmiers over. Return to the oven and cook for a further 5–8 minutes until puffed up and golden. Transfer to wire racks to cool. Serve dusted with icing sugar.