Christmas is coming...     Nigel Slater shares the flavours that, for him, make Christmas a truly delicious season. Slater shows how to cook for both entertaining and self-indulgence, filling the kitchen with tastes and smells to evoke the spirit of the season and serving up food designed to bring comfort and joy. Nigel also makes a culinary trip to Norway and goes in search of a very special Christmas tree. He shares his favourite festive treats that make Christmas…