Mushrooms on toast with bone marrow and beurre blanc – Gourmet Traveller

Ingredients

• 24 2cm-long pieces of middle-cut bone marrow (see note)
• 24 open chestnut mushrooms, stalks removed
• 60 gm unsalted butter
• 6 slices toasted bread and chervil sprigs, to serve
• Beurre blanc
• 3 golden shallots, finely chopped
• 4 tsp white wine
• 2 tsp white wine vinegar
• 2 tsp heavy cream (45% milk fat)
• 500 gm unsalted butter, diced