In a large mixing bowl combine the butter, flour and 1⁄4 tsp salt. Rub together using your fingertips and thumbs until the butter has disappeared into the flour and the mixture resembles fine crumbs. Alternatively, if you have a food processor, simply pulse the butter and flour until crumbly.
Using a table knife, stir in 4 tbsp cold water until the mixture forms an even dough. If using a food processor, add the water and pulse until the mixture comes together in a ball. Without kneading, use your hands to shape the pastry into a disc, then wrap in clingfilm and chill for 15 minutes.
Using a rolling pin, roll out the pastry to a circle large enough to line a loose-bottomed fluted tart tin, size 20cm, x 3.5-4cm (8in x 1 1/2in). Drape the pastry over the rolling pin and lower it into the tin, leaving an overhang. Pull off a little piece of pastry from the overhang, roll into a ball and use to gently mould the pastry into the sides of the tin (this will prevent your fingers perforating the pastry).
Roll the rolling pin over the tin to remove the excess pastry, then pinch the pastry up against the side of the tin so it stands a little above the rim (about 2mm). Prick the base with a fork and chill for at least 20 minutes or overnight.
Meanwhile preheat the oven to gas 6, 200°C, fan 180°C. Line the pastry case with a large piece of foil and fill with ceramic baking beans or rice. Place the tin on a baking tray and bake for 15-20 minutes, until the pastry is pale and feels sandy to the touch.
Take the pastry case out of the oven, carefully remove the baking beans (or rice) and piece of foil, then return to the oven for a further 10 minutes until golden.
Brush the inside of the pastry case with the egg white (reserve the yolk for the filling) and cook for 2 minutes more, until shiny. This will create a watertight seal before the liquid ingredients go in.
To prepare the filling, heat the oil in a frying pan and cook the diced bacon over a medium heat for 6-8 minutes or until cooked and golden. Meanwhile beat the eggs, leftover egg yolk and cream in a large jug, season generously and set aside until needed.
Reduce the oven temperature to gas 3, 170°C, fan 150°C. Scatter the cooked bacon over the pastry case then carefully pour in the egg mixture. Bake for 35 minutes or until the filling is golden, with a slight wobble in the middle when gently shaken. Leave to cool in the tin, before slicing and serving warm or at room temperature.
Freezing and defrosting guidelines
Once the dish has cooled completely, transfer it to an airtight, freezer-safe container, seal and freeze for up to 1-3 months. To serve, defrost thoroughly in the fridge overnight before reheating. Loosely cover with foil and bake until dish is thoroughly heated through. Reheat until piping hot.
See more Picnic recipes
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.