Preheat your toastie machine. Cut the sheet of pastry into 4 squares, each the same size as the square in your toastie machine.
Divide the mincemeat between two of the pastry squares. Use a little of the beaten egg around the edge of the pastry, then press another square on top to create a parcel.
Carefully place these in your toastie machine and cook for 5-6 minutes until golden brown and cooked through.
Meanwhile, whip the mascarpone with the whisky. Serve the toasties cut in half with a spoonful of the mascarpone cream, then dust lightly with icing sugar.