A creamy pie with a lovely flaky crust.
Using a pastry fork or fingers, blend the butter, salt and flour until the mixture resembles small breadcrumbs.
Add the water bit by bit to the mixture, using your fingers to incorporate the water into the pastry. You may need more than 2 tbsp but add water until the dough comes together.
Roll out thinly and using a cookie cutter, cut to the size you need.
Melt the butter in a saucepan. Sauté the garlic and mushrooms until the mushrooms start to brown. Add the leeks and oregano. Cook for a few minutes.
Add the flour and mustard. Stir while it cooks for a few minutes so the flour is cooked thoroughly.
Add the white wine then season with sea salt and pepper. Add the milk and bring to a boil. Don't have it a rapid boil or it will boil over. To finish add the parmesan cheese.
Fill four ramekins with the filling. Top with the cut pastry. Use a knife to put slits in the pastry and then brush the pastry with milk.
Bake at 400F/200C until the pastry is golden and flaky.