Heat 15 g of the butter with a tablespoon of olive oil in a large saucepan, then add the leeks. Cover the pan and cook the leeks over medium heat until tender then transfer them to the plate with a slotted spoon.

Turn up the heat and add the mushrooms to the pan. Cook them quicklly until they are lightly browned.

Pour Over the wine bring to the boil and allow it to bubble for a couple of minutes, then add the stock, season with plenty of salt and pepper and put the leeks back in the pan simmer for 10 minutes.

To make the topping, put the flour into a bowl and a generous pinch of salt. Remaining 50g of butter and rub it into your flour with your fingertips. Mix egg with buttermilk, add this to the flour and butter then mix to firm a sticky dough.

Preheat the oven to 200 c fan 180c/ gas 6 airfryer 196c roast setting.

To assemble put a filling in a deep oven proof dish dropped tablespoons of the cobbler topping over the filling spacing them out well. As they will spread while they cook.
oven for about 30 minutes until the topping
Is well risen and Golden brown.

If you don't mind extra calories you can put grated cheese over.