Remove refrigerated pie crust from package, and follow manufacturer's suggestions for unrolling crust. Set aside.

Combine nutmeg, ginger, and 2 tablespoons sugar in a small bowl.

Peel, quarter, and core 4 pears. Slice each quarter into 3 slices, from core end to bottom, and place in a large bowl. Cut remaining pear in half; peel, and core one half and add to the bowl. Peel, core, and slice the other half as directed above and add to the bowl. Drizzle pears with bourbon and sprinkle with spice-sugar mix, tossing to evenly coat.

Melt butter in a 9-inch cast-iron skillet over medium heat. Add 2/3 cup white sugar and salt to the melted butter, stirring to combine until mixture bubbles, 2 to 3 minutes. Place the single pear half in the center of the skillet. Fan remaining pear slices around the center, core end to the outside of the skillet and stem end toward the center. If possible, turn the pieces in the same direction. Keep adding pear slices, filling in any gaps, until they are all in the skillet.

Reduce heat to medium-low. Cook, undisturbed, until pears are fork-tender and color develops to the liquid, about 20 minutes.

Preheat the oven to 375 degrees F (190 degrees C). Place a baking sheet on a rack in the lower third of the oven.

Remove skillet from heat and place unbaked pie shell on top of the fruit, using a fork to tuck the edges of the pie shell toward the bottom of the skillet. Place skillet on the prepared baking sheet in the preheated oven. Reduce temperature to 350 degrees F (175 degrees C).

Bake until crust is brown, 28 to 30 minutes. Remove from oven. Place a heat-safe plate, larger than the skillet, upside down over the crust.

Use oven mitts to grab the plate and skillet together and quickly flip the skillet contents onto the plate; this move is tricky and requires some forearm strength and dexterity. After the flip, if the contents are not centered on the plate, use a spatula to gently move to the center. Add any fruit that remained in the skillet, and drizzle any remaining liquid over the top of the tarte tatin.

Allow to sit 15-20 minutes, then serve warm.