I'm not sure where you live.. but are you friendly with any local butchers? If not, find one and just go in and ask if they'll bandsaw it for you into a couple of 5" pieces. Believe it or not it's actually more difficult to get a marrow bone cut in half, like a boat, as it's dangerous for the butcher. If you can't find one then grab a saw, lady! :) Take the rounds, oven temp to 450, on a foil lined baking sheet, or a pie pan lined in foil, standing up. It should only take about 15 minutes but as soon as you see the marrow start to separate from the bone, take it out. You don't want all that tastiness to leak out. Make a nice herb salad dressed with lemon vinaigrette. Now: spoon, scoop marrow, top with a little salt - Kosher or Sea, a little herb salad, eat up! Ok. Now I'm hungry :) Good luck!