Place the butter and flour into the bowl of a stand mixer and mix until fairly well combined. Add the salt and mix. Heat the milk very gently until lukewarm and take off the heat. Add the yeast and sugar and add to the dry mixture, adding the eggs at the same time. Mix on low with the dough attachment for 5 - 10 minutes until the dough has become silky and smooth.
Transfer to an oiled bowl, cover with cling film, and let the dough rise until doubled in size (about an hour, but up to two). Gently push down the dough, turn out of its bowl and roll out into a large rectangle, about 45cm x 30cm.
Preheat the oven to 180C/350F/gas mark 4.
Filling
Mix together the mincemeat and cranberries and spread over the rolled out dough. Roll dough up lengthways into a long sausage making sure to keep the roll tight.
Cut into 12 even pieces and and place into a 23cm round springform cake tin. Allow to prove for 35 - 40 minutes or until nearly twice their original volume. Brush with milk and sprinkle with demerara sugar. Bake for 30 minutes.
Icing
Meanwhile mix together the royal icing sugar and brandy to form a paste with a drizzling consistency - you may need to add water to achieve the right consistency. Take the rolls out of the oven and drizzle with the brandy icing.
