Take 6 medium onions, about 75-100 g (3-4 Oz), and cut the stalk ends level. Place on a baking sheet and bake until soft, for about an hour at 200°C/400°F/gas mark 6. Cut a lid off each onion, scoop out most of the centre, leaving one or two layers as a wall. Blend the onion centres until smooth, mix with a little cream or grated cheese, or if you have it, potato and cheese purée, put the mixture into the onion skins and return the onions to the oven for 5 to 10 minutes for the flavours to mingle. Serve as a separate course or as an accompaniment.