Make the pastry: Mix the flour, salt and shortening until it resembles coarse meal. Using a fork, mix in water, one Tablespoon at a time, until dough clings together and cleans easily from the bowl. You do not need to use all the water. Use just enough to make a dough. Gather it into a ball, wrap with plastic wrap and pop it in the fridge for 30 minutes.
Divide dough in two if making two quiches, or leave as one ball if making a 12-inch tart. Flour a work surface and roll dough into circle about 2-inches larger than your pie or tart pan. Dough should be about 1/8" thick. Lightly grease the pie plate, then flip the dough onto rolling pin and transfer to pie plate(s). Refrigerate while you make the filling.
Make the filling: In a skillet over medium heat, cook bacon for 3-4 minutes or until the point where the fat has cooked off, but before it is starting to brown. Add the diced onion and cook together with the bacon, stirring regularly, until bacon is just crisp and onions are browned. Remove from heat. Spoon of the fat and discard (Just tilt the pan and the fat will run to the low point, where you can easily spoon it off). Put the bacon/onion mixture into a bowl to cooled to room temperature.
Preheat oven to 375F. (regular bake setting/not fan assisted)
Prepare custard by combining cream and eggs together in a large measuring cup or similar with a spout for pouring. Whisk together well with a whisk or fork. Season with salt and pepper, keeping in mind that there will be some salt from the bacon already in the mix, so you don't want to add too much salt.
When bacon/onion mixture is cooled, scatter over bottom of pie/tart shell (dividing between the two if making two regular pies). Top with shredded cheese (again, dividing between two, if making two). Pour custard over-top (dividing, if necessary). Custard may only come about 1/2-2/3 up the pastry side. Don't worry, it will puff up as it bakes.
Bake in preheated oven for about 40-45 minutes, or until set and quite golden in spots. Remove from oven and let stand 5-10 minutes, before slicing and serving.
Notes
This quiche is best enjoyed freshly baked. You can fill the quiche, cover and refrigerate, to bake off later. Refrigerate unbaked quiche up to 8 hours. Baked quiche can be refrigerated, well wrapped, for 2-3 days.You can also pre-bake the quiche and re-heat. To reheat, cover it with foil and bake at 325 degrees for about 15 minutes, until just heated through.Quiche also freezes well, either unbaked or baked. Freeze up to 3 months.Be sure to read the notes above this Recipe Card, where I share some valuable tips, options, substitutions and variations for this recipe!