My mother used to make this when I was a child. Apologies for the imperial measurements but I've been making this since before metrication!
8 ounces plain flour
4 ounces margarine cut into cubes
2 - 4 tablespoons water
3 rashers streaky bacon, chopped
4 ounces grated Cheddar cheese
2 teaspoons chopped onion
To make the pastry, combine the flour, salt and margarine. Rub until it resembles fine breadcrumbs. Add the water a spoonful at a time until it comes together in a dough. I use a stand mixer on speed 2 with a K beater. Place in the fridge for 30 minutes wrapped in cling film.
Pre heat the oven to 200 degrees (not fan). Roll out the pastry to fit a 7-8" flan dish and bake blind for 10 minutes.
Fry the bacon until crisp. Beat the eggs with some seasoning then add the hot milk, bacon, cheese and onion. Spoon the mixture into the part baked pastry case, lower the oven to 180 degrees and cook for about 30 minutes until set.
This can be served hot or cold with salad. You can always swap the bacon for a vegetarian option if you prefer.