I was looking for something to do with a marrow. Nigel Slater had a few things to say here. So I did something similar to his stuffed with lentils recipe.
I fried onion, carrot and garlic in a pan and then added a cubed potato, about250g of lentils and about 50g of basmati rice. I stirred in 2 or 3 teaspoons of Harissa, a veggie stock cube, a tin of chopped tomatoes and enough boiling water to cover everything. I simmered this for about 15 minutes topping up with water as needed. I added in some chopped spring greens and cabbage, but I guess whatever green vegetables you have handy would work. Cook for another 5-10 minutes.
Cut the marrow in half lengthwise and scoop out the seedy bit. Put the two half in baking tray and then spoon in the lentils. Cover with foil and bake for 30mins. Remove the foil and grate some cheese over the top and put it back in the oven for 15 mins. Eat. Beware the marrow gets very hot.
We decided this would be much better and easier to eat with the marrow peeled and chopped and mixed in with the lentils.