http://www.waitrose.com/food_drink/recipes/recipesearch/recipe/0607ss46-r02.asp
Did this the other night using a not-very-enormous marrow and it was very good. In fact, Waitrose's website is terrific for us allotmenteers as you can search out recipes by keyword (eg 'name-your-glut-veg-or-fruit')!
I've just made 16 jars of lemn/orange/lime curd from EJ's recipe on http://www.allotments4all.co.uk/joomla/component/option,com_smf/Itemid,72/topic,16848.0
great way to use up marrows, hope it tastes as good as it looks ;D
Kathi