1. Preheat the oven to 180°C/350°F/gas mark 4. Heat a little olive oil and the butter in a frying pan until foaming then add the leeks and fry gently for 10 minutes until soft. Add the garlic and fry for a further 2 minutes. Add the mushrooms and cook for 5 minutes. Remove from the heat, stir in the goats cheese then season to taste. Tip the mixture into a 2 litre square Pyrex dish.
2. In a small Pyrex bowl, mix together the breadcrumbs, parsley and parmesan cheese then sprinkle over the top of the leek and mushroom mixture. Bake in the oven for 20-25 minutes until the top is golden brown and crispy. Leave to cool for 10 minutes before serving.