In a mixing bowl, combine flour, cold butter, salt, and baking powder until the mixture resembles coarse crumbs. Gradually add ice-cold water, mixing until the dough forms. Wrap the dough in plastic wrap and refrigerate for at least 2 hours.

Preheat your oven to 375°F (190°C).

Remove the dough from the refrigerator and roll it out on a lightly floured surface until it's about 1/8-inch thick. Transfer to a pie plate.

Place the prepared crust in the preheated oven and par-bake for 10 minutes, or until it starts to set.

Peel and slice the russet potatoes into thin rounds. Cook in salted boiling water for about 5 minutes until just tender. Drain and set aside.

In a large bowl, whisk together the eggs, half and half, heavy cream, Swiss cheese, green onions, bacon, salt, pepper, and nutmeg.

Gently fold the boiled potato slices into the egg mixture. Pour the filling into the par-baked crust.

Return the assembled quiche to the oven and bake for 30 to 40 minutes, until the filling is set and golden brown.

Let the quiche cool for about 10-15 minutes before slicing.