Squeeze the lemon into a medium bowl. Using a mandolin (set on the second setting), slice each quartered apple into 1/8-inch slivers. As the apples are sliced, transfer them to the bowl and toss them in the lemon juice; this will prevent them from browning. (Reserve one quarter of an apple for the center - we're going to slice that later). Repeat until all the apples are sliced and in the bowl. To the bowl, add the brown sugar, flour, cinnamon, nutmeg and salt. Toss until evenly coated.
Roll out your pie crust and place it in a 9-inch pie pan or 9-inch tart shell. (I chose the latter.) Arrange the apple slices side-by-side, starting closest to the edge of the tart shell. For the second layer, arrange the slices, overlapping them in concentric circles. As you get to the center, you'll need apple slivers that are very thin. Slice the reserved quarter of an apple very thinly (on the mandolin's first setting) and arrange it until the gap in the center is completely closed.
Transfer the pie to the freezer and freeze until firm, about 1 hour. Preheat your oven to 400 degrees F. Brush the edges of the crust with egg wash and place in the oven for 25 to 30 minutes, checking on it at the 20-minute-mark to make sure all is ok, until the apples are lightly golden brown and the edges of the crust are browned. Allow to come to room temperature on a cooling rack.
Meanwhile, let's make the bourbon glaze. In a heavy-bottomed medium, placed over moderately high heat, pour in the sugar. Cook until the sugar begins to melt and turns a light golden brown around the edges. Using a silicon spatula, begin to stir until the sugar melts completely and turns a lightly golden brown. Cook for an additional 30 seconds or so until the sugar turns a golden brown color. Immediately take the pan off the heat and stir in the butter. Once the butter has melted, pour in the bourbon and water. The mixture will bubble up, not to worry - this is normal, just keep stirring until smooth. If the mixture seizes, place the mixture over very low heat and keep stirring until it becomes smooth. The mixture should be thin.
Brush the apples liberally with the warm glaze. You may have a tablespoon or two of extra glaze. I say put it your coffee!