If making a homemade pie crust allow at least 3 hours to chill before rolling out.
On a lightly floured surface roll out the pie crust into an 11" circle. Press into a 9" tart pan with removable bottom or a 9" shallow pie dish. Use a fork to poke several holes in the bottom of the crust. Freeze the crust for at least 30 minutes and up to 24 hours.
Cover the crust with parchment paper and fill with pie weights or dried beans/rice. Preheat oven to 425°F. Keep the crust in the freezer while the oven
If using a tart pan with a removable bottom, place the pan on a large rimmed baking sheet. Blind-bake the crust for 15 minutes. Remove the parchment paper and weights or dried beans/rice and bake for 5 more minutes.
Reduce the oven temperature to 375°F.
While the crust is blind-baking prepare the filling ingredients. In a large pan, cook the bacon until crispy on both sides. Remove and set aside to cool. Discard all but 1 tablespoon of the bacon grease. Add the chopped onions and saute until soft. About 2-3 minutes. Remove from heat and set aside.
In a medium bowl, whisk together the eggs, half&half, salt, pepper, and paprika.
Chop the bacon into bite-size pieces and spread evenly in the bottom of the prebaked pie crust. Add the onions and the shredded cheese. Pour in the egg/milk mixture. You may have some egg/milk mixture leftover. Don't overfill, the filling will puff up somewhat during baking.
Bake for 40 minutes. The filling will be slightly puffed up and a knife inserted into the center should come out clean.
Allow the quiche to cool slightly before serving, garnish with more chopped cooked bacon and chopped fresh parsley.