Preheat oven to 375°F.
Roll out the pie dough on a lightly floured work surface and transfer to a 9-inch deep dish pie plate. Fold the crust under and crimp with your fingers or a fork. Poke holes all over the sides and bottom of the crust and chill in freezer for 15 minutes. Transfer the chilled pie crust to a baking sheet. Line with parchment paper and fill with pie weights or dried beans. Bake until lightly golden brown, 20 minutes. Remove from the oven and allow to cool slightly before removing the parchment paper and weights or beans. Set aside.
Set a medium skillet over moderate heat with the butter. Once melted, add in the onion and garlic and cook until translucent, 3 to 5 minutes. Add in the shredded chicken, hot sauce and a pinch of salt and pepper. Cook until the sauce has almost evaporated, 5 to 8 minutes. Turn off the heat and transfer the chicken to the cooled pie crust.
In a large glass measuring cup or bowl, whisk together the eggs, milk, heavy cream and a pinch of salt and pepper. Carefully pour into the pie crust over the chicken. Sprinkle with cheese and transfer to the oven. Bake until golden brown and the quiche has set, 45 to 50 minutes. The center will jiggle slightly when gently shaken, but not too much. Remove from the oven and allow to cool for 10 minutes.
In the meantime, in a large bowl, toss together the celery, carrot, scallions, radishes, oil, vinegar and a pinch of salt and pepper. Pile the salad in the center of the quiche. Drizzle with ranch and top with blue cheese or feta. Slice and serve immediately. Serve either warm or at room temperature. Enjoy!