Saffron risotto

Preparation:

Preparation: Filter the marrow to remove all traces of blood and bone. In a saucepan, brown the chopped onion together with the ox marrow and butter, adding a bit of broth. Put the rice, then add the broth and wine; add broth and wine each time the rice dries up. Halfway through cooking, add the saffron diluted with broth and the remaining butter along with the grated cheese. Serve the risotto al dente, possibly covered with flakes of white truffle.