Method

• 1

  Preheat the oven to 180C/350F/Gas 4. To make the pastry, mix the flour, thyme and Parmesan-style cheese in a large bowl then use your fingers to rub in the butter until the mixture resembles breadcrumbs. Make a well in the middle, add the egg yolks and gently bring the mixture together, adding a little of the milk if required. Wrap in clingfilm and refrigerate for 30 minutes.

• 2

  Roll out the pastry and transfer to the tin and trim any excess pastry – the pastry is very short, so take care when moving it. Refrigerate for about 15 minutes.

• 3

  Bake blind for approximately 15 minutes. Take out of the oven, remove any baking parchment or baking beans and bake for 15 minutes until golden.

• 4

  To make the filling, heat 3 tbsp of the oil in a large pan and cook the leeks, stirring, until they soften and begin to caramelise. Season with salt, transfer to a large bowl and set aside.

• 5

  Heat the remaining oil in the pan, add the mushrooms, season and cook, stirring, for 2-4 minutes. Add the garlic and butter and cook, stirring, for two minutes. Remove the pan from the heat and add the mushroom mixture to the leeks. Leave to cool then drain off any excess liquid. Stir in the remaining ingredients, pour into the pastry case and bake for 20 minutes or until the egg is set.