1. Set oven at 405ºF. Place the marrow bones in a roasting pan with the widest side of the bone on the bottom. Roast for 20 to 25 minutes, or until the bone marrow is soft and jiggly.
2. While the marrow is roasting combine parsley, lemon juice and capers in a bowl and season to taste with salt and pepper.
3. When you’re ready to serve top each bone with parsley mixture. Using a small knife or spoon spread the marrow onto a slice of toast and season with salt to taste.