Make pastry following the recipe above to the end of step 4. Roll out pastry on a lightly floured surface to a 15 x 40cm rectangle, about 3mm thick. Line a shallow 10 x 34cm (base measurement) fluted tart tin, with removable base, with pastry and trim any excess. Place in the fridge for 30 minutes to rest.

Meanwhile, preheat oven to 200°C. Melt the butter in a large frying pan over medium heat until foaming. Add the leek and bacon and cook, stirring, for 5 minutes or until leek softens. Remove from heat.

Cover pastry base with baking paper and fill with pastry weights, rice or dried beans. Bake in oven for 10 minutes. Remove paper and weights, rice or beans. Bake for a further 8 minutes or until golden. Remove from oven and reduce oven temperature to 160°C.

Spread mustard over pastry base. Top with the leek mixture and brie slices. Whisk the eggs and cream together in a bowl. Season with salt and pepper. Pour the egg mixture into the pastry case.

Bake in oven for 25-30 minutes or until just set. Serve warm.