Roast the marrow bones

• Place the split marrow bones cut side up on a baking tray.
• Roast until the marrow is soft and loosened from the bone.

Scoop out the marrow

• Let the bones cool slightly, then scoop the marrow out with a small spoon.
• Discard any bone fragments and set the marrow aside.

Soften the aromatics

• Melt a little butter in a saucepan over low heat.
• Cook the shallot and garlic gently until soft and fragrant, without browning.

Melt the marrow into the butter

• Add the marrow to the pan and melt it into the butter over low heat.
• Stir in the salt and pepper, then take the pan off the heat.

Blend and finish

• Whisk the warm marrow butter with the remaining softened butter until smooth.
• Stir in the parsley and lemon juice, then taste and adjust the seasoning.

Chill and serve

• Pour the butter into a small dish or roll it in parchment into a log.
• Chill until firm, then slice and serve on steak, bread or vegetables.