the only good AND EDIBLE thing to do with a marrow, is pick and prepare it while it's still small enough to be a courgette. Any bigger than that and it's just watery and horrible no matter which way you try and dress it up.
It might at a stretch be possible to make it into a boring but healthy soup, if you chucked in enough flavours (herbs? a gazillion sweated onions? several pints of cream?) or to disguise chunks of it in a veg curry. Otherwise it's just rank and deserves to be walked straight to the bin.
there is no excuse for marrow.