Jane Grigson's vegetable book if really handy for courgette recipes but also has advice for those of us who have left them too long on the plant:
'For a small family faced with a huge marrow, it is best to slice it down into rings about 2-3cm thick, allowing one or two per person. Do not peel the rings, but blanch them for five minutes only, after removing the seeds in the middle. Place the rings in a buttered dish and fill the centres with stuffing, allowing it to spread a little over the marrow in a domed shape. Allow 45-60 mins at 190C/375F.' Sounds like a plan.