I browned a packet of beef mince with an onion and 3 garlic cloves. I added a small carton of pasata and the following herbs, oregano, basil, thyme and a little bit of chilli powder and cumin for a little kick optional with a good splash of Worcestershire sauce. I left it to reduce a little and then left to cool down. I mixed through 2 whisked eggs. This helped to stick it all together in the marrow.
I cut the marrow in half length ways and removed the inner core and seeds and sprinkled with salt. After stuffing the two marrow halves I covered in 42g of light cheddar and put in the oven at 180 for 1 hour. You might want to cover it with some foil for a bit in the oven to prevent the top from browning too much!
If you have any marrow left you could use it as the layering in a moussaka. That's how I get my sons to eat it without knowing the difference.
I just slice it thinly and lay it on a baking sheet that I've 'fry lighted' and let them soften in the oven for 10 mins and then use them inbetween the layers, alternating with thinly sliced potato. Is yum!