Sift the flour, baking powder, salt and spices into a large mixing bowl. In a separate large bowl, beat the butter and sugar until light and fluffy, then gradually beat in the egg. Stir in the dry ingredients until you have a smooth dough. Gather together and press into a flattish disc.
On a floured surface, roll out the dough to just under 1cm thick. (If it’s too soft to handle, wrap it in cling film and chill for an hour first.) Either cut out circles, then press into oiled heart-shaped moulds (see tip), or use cutters to stamp out heart shapes, then chill for at least 1 hour.
Heat the oven to 180°C/fan160°/gas 4. Put the biscuits on lightly greased baking trays and bake in batches for 7-10 minutes until dark golden and crisp. Cool completely on wire racks, then dust with icing sugar and serve.
