Preheat your oven to 220°C (200° for fan-assisted ovens) Gas Mark 7.
Unroll your puff pastry sheet, leaving it on the baking paper.
Spread the mincemeat evenly over the puff pastry, leaving about a cm free around the edges.
Roll the pastry into a Swiss roll, starting from a long side nearest to you.
Using a sharp knife, cut the roll into slices about 1.5cm thick.
Place the slices on a baking sheet,amd brush the edges with a beaten egg.
Sprinkle with Demerara Sugar (optional).
Bake on a lined baking sheet for 12-15 minutes until golden brown.
Cool on a wire rack.
Optional: Dust with little icing sugar for an added festive touch.