Potato and mushroom pies

Method
Prep:25min  ›  Cook:30min  ›  Extra time:1hr  ›  Ready in:1hr55min 

1. In a food processor, blend 300g flour and 1 teaspoon salt. Add butter, and process in short bursts until the the mixture is crumbly. Should take only a few bursts to make the pieces of butter a little smaller than pea-sized. Add in chilled water, about 150 ml, and quickly process. Add more water if needed, tablespoon by tablespoon, until the mixture starts to form a soft dough. Form into a ball and wrap in cling film. Place in the fridge for 1 hour.
2. Fill a large pot with water and bring to the boil. Add potatoes and cook until just tender. Drain, and set aside.
3. Meanwhile, melt 100g butter in a large frying pan. Add leeks, cabbage and mushrooms, and cook until soft. Stir in garlic and thyme and cook for a few more minutes. Mix in bouillon paste and enough water to make a thickish sauce. Stir in potatoes and remove from heat. Spoon mixture equally into two pie dishes.
4. Roll out 1/2 of the pastry on a floured surface to form a rough circle about 3mm thick. Cover one pie dish with pastry, crimp edges and make several small cuts in the top to allow steam to escape while cooking. Repeat with remaining ingredients.
5. Bake for 30 to 40 minutes, or until golden brown.