Cut sheets of filo pastry into 9 cm/3½ in squares. Cover with a dampened cloth. Lightly brush one square of filo pastry with melted unsalted butter which has had the froth removed. Place a second square diagonally on top so that there is a triangle shape on top of a square shape. Lightly brush with melted butter and repeat with another layer but do not butter; the third layer should be placed so that it is a triangle slightly off centre. Try to touch the layers as little as possible, to ensure the pastry is light and crisp.
Divide the layers into two lots, bases and lids. Place the bases in non-stick tart tins, put a little mincemeat in the centre, brush a little butter in a ring on the pastry lid and gently press the buttered part onto the filo base. Brush the top lightly with butter.
Bake in an oven set at 190°C/375°F/gas 5 for 8 minutes, until golden brown. Liberally dust the mince pies with icing sugar. These mince pies, which are light and delicate, will have the appearance of Christmas roses.