Method

• 1.
  Place both quantities of bones in separate large bowls, cover with cold salted water and leave for 24 hours, changing the salted water three times. Drain and remove the marrow from the bones (reserve bones for stock). Finely chop the smaller amount of marrow. Cut the larger amount into 1cm pieces. Set both aside.
• 2.
  Heat a deep saucepan over medium heat. Add the breadcrumbs and toss for 3-4 minutes until toasted. Set aside. Wipe the pan clean and return to medium heat. Add butter and finely chopped marrow and cook, stirring frequently, for 1-2 minutes until melted. Add toasted breadcrumbs, reduce heat to medium-low and cook, tossing frequently, for 2-3 minutes until golden.
• 3.
  Stir in 1/2 cup (125ml) stock and stir slowly for 15-20 minutes until stock is absorbed. Stir in another 1/2 cup stock and repeat 4-5 times with remaining stock until breadcrumbs are saturated (you may not need all the stock). Season to taste and keep warm.
• 4.
  For the fried bone marrow, place the marrow in a bowl with the cornflour and toss to combine. Melt the butter in a frypan over medium-high heat. Add the marrow mixture and cook, tossing frequently, for 2-3 minutes until golden. Transfer to paper towel, season to taste and set aside until ready to serve.
• 5.
  Heat oil in a medium frypan over high heat. Add the mushrooms and cook, tossing occasionally, for 4-5 minutes until golden and cooked. Season to taste.
• 6.
  Divide soup among bowls and scatter with mushrooms, parsley and fried bone marrow. Serve immediately.