To begin: Pre-heat the oven to 100˚C Steam only setting. Peel the potatoes and place on a large perforated tray. Finely slice the leek and cut the kernals away from the corncobs and place on the same tray as the potatoes. Place in the oven for 10 minutes. Once cooked remove the corn and leek from the tray and set aside, return the potatoes for a further
20-25 minutes until fully cooked.

Cut the fish into large chunks and chop the prawns in half and place in a large mixing bowl, add roughly chopped parsley and tarragon and season with salt and pepper, add the steamed corn and leek and mix well.

Pour milk and stock into a jug and mix. Place the saucepan over medium heat and add a little olive oil, saute the shallots and add 40gm butter, once butter has melted and shallots softened add the flour and cook out to make a roux. Pour the milk/stock mixture over the roux and whisk until smooth. Set the sauce aside to cool for 10 minutes.

Pour the slightly cooled sauce over the fish mixture and mix well with a spatula, check and adjust the seasoning and transfer the mixture to a ceramic dish.

Once the potatoes have cooked remove and mash with ricer or potato masher. Add the remaining butter and milk to the mash along with seasoning and mix well. Finally add the egg yolks and transfer to a piping bag.

Pipe the mashed potato on top of the fish mixture and place into an pre-heated on Combi Mode (75% Steam) for 20-25 minutes until golden brown on top.

Remove from the oven and let rest for 5 minutes before serving with a crisp green salad and crusty bread.