Can't decide between a quiche Lorraine or Florentine for your next brunch? Add bacon and spinach to the basic filling for the best of both worlds.
Crust: Pulse flour and salt in a food processor until combined. Add butter and pulse until mixture resembles coarse meal. Whisk together egg yolk and 2 tablespoons ice water. Add to flour mixture and pulse until moist crumbs start to form (no longer). Transfer mixture to a piece of plastic wrap, and using wrap and your hands, form into a disk. Refrigerate, wrapped, at least 30 minutes and up to 4 hours.
On a lightly floured work surface, roll out dough to an 11-inch round. Transfer to a 9-inch pie plate; trim edges to a 1-inch overhang. Tuck overhang under and crimp as desired. (To create arc pattern, press a spoon into dough.) Wrap in plastic; freeze at least 30 minutes and up to 3 days.
Preheat oven to 400 degrees. Line crust with parchment and fill with dried beans or pie weights. Bake until dough underneath parchment is dry, 25 minutes; remove parchment and beans. Bake until golden, 8 to 10 minutes more. Let cool slightly.
Filling: Reduce oven temperature to 375 degrees. Whisk eggs until smooth, then whisk in cream, milk, 1 1/2 teaspoons salt, and 1/2 teaspoon pepper. Stir in half of bacon and cheese. Pour custard mixture into crust, stopping just short of the top; be careful not to overfill. Press spinach into custard, leaving some poking out from top.
Sprinkle with remaining bacon and cheese. Bake 10 minutes at 375 degrees, then about 55 minutes at 325 degrees. Let cool about 1 hour before serving.