Heat oven to 180C/160C fan/gas 4 and put a baking tray in the oven to heat up. On a lightly floured surface, roll out two-thirds of the pastry to a circle about 0.5cm thick. If you’re adding a spiced flavour to your pastry, sprinkle with the cinnamon or nutmeg, fold in half and repeat, then roll it out again to a circle about 0.5cm thick.
Press the pastry into a 23cm metal pie tin or tart tin and trim off any excess pastry hanging over the edge. If you’re using a deep tin, roll the edges down a little to make a lip (you only want to make a shallow tart). Spread the jam over the pastry base.
On a lightly floured surface, roll out the remaining pastry to a thickness of 0.5cm and use small cookie cutters to stamp out shapes. Re-roll the trimmings and cut out more shapes if needed. Arrange the pastry decorations over the jam layer.
Put the tin on the hot baking tray and cook for 40 mins, then leave to cool for 15 mins. Dust the pastry toppings with icing sugar. Serve warm or cold with custard, cream or ice cream.