Arrange a rack in the middle of the oven, set a baking sheet on rack, and heat the oven to 375°F.

Gently roll the pie crust out to about 12 inches in diameter and lay it in a standard 9-inch pie pan.

Press the pie dough into the pan, then roll or trim the edges to fit the lip of the pan.

Use your fingers or a fork to crimp the crust.

Line the pie dough with a circle of parchment paper.

Fill the pie shell with beans, sugar, or pie weights.

Place the crust on the preheated baking sheet.

Par-bake until the edges are beginning to brown, 18 to 20 minutes.

Meanwhile, start the filling.

Cook 4 slices chopped thick-cut bacon and 2 thinly sliced shallots in a large skillet over medium heat, stirring occasionally, until the bacon is crisp and the shallots are super tender and just starting to caramelize, 20 to 25 minutes.

Remove from the heat.

Remove the par-baked crust from the oven but leave the baking sheet in the oven.

Reduce the oven temperature to 350ºF.

Carefully remove the parchment paper and pie weights from the pie crust.

Cool the crust and the filling for at least 15 minutes.

Meanwhile, make the egg custard.

Whisk 3 large eggs until homogenous in a large bowl.

Add 1 ½ cups half-and-half, ½ teaspoon kosher salt, ¼ teaspoon nutmeg, and ¼ teaspoon black pepper and whisk until well combined.

Sprinkle 2 ounces finely grated Gruyère cheese into the pie crust.

Pour the custard over the cheese.

Sprinkle with the cooled bacon-shallot mixture.

Bake on the hot baking sheet until the quiche is browned around the edges and is mostly set but has a gentle wiggle to the center, 30 to 40 minutes.

Let the quiche cool for 2 hours.

Sprinkle with thinly sliced scallions or chives if desired before slicing and serving.