Preheat the oven to 180°C/350°F/Gas Mark 4. Lightly grease and base line a shallow rectangular baking tin approximately 35 cm x 25cm. Sift the flour, baking powder and cinnamon together into a bowl.
Using an electric whisk beat the butter, sugar and orange rind together in a bowl until light and fluffy. Beat in the eggs and soured cream. Once completed fold in the flour mixture and mulled wine gradually.
Pour the mixture into the prepared tin and bake for 25 minutes until golden and cooked through. Cool for 5 minutes in the tin before turning out onto a wire rack to cool completely.
To make the frosting, beat the butter and chestnut puree together in a bowl using an electric whisk. Gradually beat in the sugar then the whiskey.
Using a plain pastry cutter, slightly smaller than the top of the jars, cut out circles from the cooled cake. Carefully fit a layer of cake in the base of each jar. Fill a piping bag fitted with a small star nozzle with the frosting and pipe a layer over the cake. Top with another circle of cake, pushing down to fit snugly. Pipe a rosette of frosting on top of each cake and secure the lid to the jar.