Prepare the pie crust as instructed and allow to chill for at least 1 hour or up to overnight.

Remove the dough from the refrigerator and allow to warm up slightly, then roll the dough on a lightly floured surface to a thickness of 1/8-inch. Transfer the dough to a 9- or 10-inch tart pan with a removable bottom, easing in the sides. Trim the dough even with the top of the tart pan and return to the refrigerator for at least 30 minutes while the oven is preheating.

Preheat the oven to 400 degrees F.

Line the chilled pastry dough with a piece of parchment paper, and fill the crust with pie weights.

Bake in the middle of the oven until pastry is nearly set, 15 to 20 minutes. Remove the parchment and pie weights and continue to blind bake the crust until it is golden, 10 to 15 minutes longer.

Remove from the oven and cool completely. Reduce the oven temperature to 325 degrees F.

When the crust has cooled, sprinkle the bacon and gruyere evenly over the bottom. Place the partially filled crust on a rimmed baking sheet.

In a medium mixing bowl, whisk the eggs together with the heavy cream, sour cream, and milk. Add the green onions, thyme, salt, cayenne, and nutmeg and whisk to combine. Pour the egg mixture evenly over the bacon and gruyere. Bake the quiche in the middle of the oven until the crust is golden and the filling is set and lightly browned in spots on the top, 40 to 50 minutes.

Remove from the oven and cool briefly before serving.