Take a bowl, add in the flour and butter, rub them together with your fingertips to mix well and form crumbles.
Next pour in a little cold water and mix it all together well. Make a large dough ball and keep it aside.
Now roll this pastry on a floured surface into a large and round shape, which would be a little larger than a 25cm tin. Then take the tart case and put the rolled pastry over it.
Scrape off the extra pastry and make sure the size of it just fits in the tart case. Then let it refrigerate for 20 mins. Also heat the oven to 200 degree celsius.
Take a pan, heat in the butter, add in the leeks and cook for 8-10 minutes till they become soft. After this time, add in the mushrooms and cook for 5 more minutes. Turn off the heat.
With a fork, prick the tart base, then line it with a foil and fill it with baking beans. Bake this tart for 20 minutes then remove the foil and beans and continue baking for another 5-10 minutes.
Take a bowl and beat in the eggs, then add in the cream. Put in the sauteed vegetables and season well. Then carefully pour this filling mixture into the tart.
Sprinkle some cheese on top and bake it for 25 minutes till it turns golden brown on top and is set.
Once cooked, leave it to cool. Then garnish with a few coriander leaves and cut in slices to serve.