Place the flour into a large mixing bowl, add the butter, and rub until mixture resembles breadcrumbs.
Add three tablespoons of cold water until the pastry comes together as a dough ball.
Roll out the dough, line a flan tin, and chill in the fridge.
Preheat the oven to 220C, then blind-bake the pastry for 10 minutes.
Reduce the oven temperature to 180C, then combine eggs, cream, salt, and pepper.
Cook the bacon until crispy, then transfer to the pastry case.
Cook the onion until golden, add to the pastry, and top with grated cheese.
Bake the quiche in the oven for 25-30 minutes until golden and set.