Note Bone marrow is available from select butchers but will need to be ordered ahead. Some butchers will remove the marrow for you. This recipe is from Marco Pierre White's Great British Feast (Orion, $55, hbk). In editing this recipe for publication we have made minor changes to bring it into Gourmet Traveller style.
As a boy, I used to go mushrooming with my old granddad and we'd return with a fishing basket full of field mushrooms - some of them huge, more than 20cm in diameter. He'd fry them up and serve them on toast; they were great days. Mushrooms and bone marrow are a marriage made in heaven. You'll need to begin this recipe a day ahead.