Heat the oil in a frying pan over a medium heat and fry the onion for 10 mins until tender. Add the leek and fry for another 10 mins until softened. Tip the vegetables into a bowl and leave to cool for a few minutes.

Heat the oven to 180C/160C fan/gas 4. Stir the breadcrumbs, sage, parmesan and eggs into the vegetable mixture and combine using clean hands. Season with salt, pepper and a grating of nutmeg. Divide the mixture into 12 portions, dampen your hands and roll the portions into small balls between your palms. Place the stuffing balls on an oiled baking tray. Drizzle with another 1 tbsp oil and bake for 25-30 mins, turning halfway through, until golden and crisp. Grate over a little more cheese before serving.