1. Place water and salt in a large baking dish. Stir to dissolve salt completely, then add marrow bones and cover with ice. Cover dish and refrigerate overnight.
2. Preheat oven to 220 °C (425 °F).
3. Remove bones from brine. Drain and pat dry. Place on a parchment-lined baking sheet and season with salt and pepper.
4. Bake in the oven for 20 minutes.
5. Meanwhile, in a non-stick skillet, add half the garlic butter and half the oil.
6. Cook mushrooms over high heat for 5–8 minutes or until browned. Season. Remove and transfer to a plate.
7. In the same skillet, add remaining butter and oil. Add onion, shallot and garlic. Cook for 2–3 minutes.
8. Deglaze with white wine and reduce by a third. Pour in broth and reduce by half. Remove from heat. Add cold butter and parsley. Mix well until everything is melted and blended.
9. When the bones are cooked, finish under the broiler for 4–5 minutes.
10. Remove from oven.
11. Garnish each bone with grilled mushrooms and sauce. Serve with toast. Spread the marrow on toast and top with mushrooms and sauce. It’s truly delicious!

Chef’s Secret

• Soaking the bones in salted brine cleans the bones and marrow while giving them a light salty taste.