Coat a 9-inch pie plate with cooking spray. Roll out the pie crust and fit it into the pie plate. Trim away any overhang and reserve for patching up any cracks that appear during baking. Meanwhile, arrange a rack in the middle of the oven and heat to 350°F.
Cover the pie crust with parchment paper and fill with pie weights or dried beans. Make sure the weights are snug against the sides of the pan. Bake for 20 minutes. Remove the weights and parchment. Bake until just starting to brown, 10 to 15 minutes more. Cool while you prepare the filling.
In a large skillet over medium heat cook the bacon until crispy – about 12 minutes. Drain the bacon onto a bowl lined with a paper towel, leaving about 1 tablespoon of the accumulated drippings in the skillet. Add the white parts of the scallions (reserve the green parts for garnish), celery, and garlic to the skillet and cook until the vegetables are just slightly soft – 3 to 5 minutes. Pour the vegetables over the bacon and set aside while making the custard. In a large bowl whisk together the eggs, cheese, heavy cream, milk and the hot sauce until completely combined. in ½ cup of the blue cheese, ¾ cups cheddar cheese, and the vegetable bacon mixture.
Sprinkle ½ cup of the blue cheese, ¾ cups cheddar cheese, and the vegetable bacon mixture into the pie crust then pour the custard over the top of the cheese and vegetables.
Bake the quiche until the edges are set but it still jiggles a little in the center, 35 to 40 minutes.
Cool for at least 15 minutes, (this helps the quiche get a bit more set as it the custard continues to cook from residual heat) but can be left overnight in the refrigerator also.
Quiche can be served cold, room temperature, or warmed. If serving warm, heat in a 300°F oven until just warm to the touch. Sprinkle the remaining ¼ cup of blue cheese crumbles, the reserved green scallions and a few cranks of fresh ground black pepper.