Core and cut 3 pounds Fuji apples into wedges with an apple slicer. Remove the peel from each apple wedge, then slice each wedge lengthwise into 3 pieces.
Add the sliced apples, 1 cup granulated sugar, 1/3 cup all-purpose flour, 1 teaspoon ground cinnamon, 1/8 teaspoon ground nutmeg, and 1/8 teaspoon salt to a large mixing bowl. Mix well to coat the apple slices, then set the bowl aside while you prepare the crust.
Roll out the bottom pie crust and place the crust in a pie plate, making sure the edges of the dough extend beyond the rim of the pie plate.
Spoon the apple filling into the crust. Gently press the apples down into the pie plate with the back of a spoon.
Slice 2 tablespoons unsalted butter and place the butter slices on top of the apples.
Roll out the top pie crust and place the top crust over the apples. Trim the edge of the dough, leaving 1/2 inch of overhang. Shape the edge of the crust and gently press the top and bottom crusts together to seal.
Cut decorations or slits into the top crust to release steam. At the very least, cut a few slits.
Melt the remaining 2 tablespoons unsalted butter. Use a pastry brush to spread the melted butter over the top crust, then sprinkle the crust with coarse sanding sugar.
Place the pie plate on a baking sheet to catch any drips. Bake the pie at 425°F for 12 to 15 minutes, or until the crust is lightly browned.
Remove the pie from the oven and cover the crust edges with strips of foil or a pie crust shield.
Reduce the oven temperature to 400°F. Return the pie to the oven and bake for 30 to 40 minutes, or until the crust is golden brown and the filling is bubbling through the slits.
Remove the pie from the oven and discard the foil. Let the pie cool on a wire rack until warm or room temperature before slicing and serving.