Preheat the oven to 170 degrees and roast the bone marrow for roughly 30 minutes
Chop the potato into cubes
Peel and remove the core of the parsnip and chop it into cubes too
Slice the leek lengthways and wash, using only the white part. Slice thinly
Steam the potato, parsnip and leek together until soft.
Take out a bowl and mash the veggies together, adding in the bone marrow, miso, egg yolk, finely chopped parsley and grated parmesan cheese. Mix well
Place in the fridge for an hour to cool & firm up Take out roughly one tablespoon of the mixture and roll into logs
Roll in finely chopped parsley & grated parmesan cheese, placing on a lined baking tray. Repeat this process until all of your mixture is finished.
Bake for 35 minutes until golden on top