Preheat the oven to 400ºF.
Combine the ground vanilla wafers and chopped pecans in a blender or food processor. Pulse once or twice to blend. With the machine running, add the butter and process until blended. Press the mixture into the bottom and up the sides of a 9-inch deep-dish pie pan and bake until golden, 10 to 12 minutes.
In a large saucepan, combine the eggnog, pumpkin, brown sugar, egg yolks, cinnamon, nutmeg, salt, and ginger and mix well. Place over medium heat and cook for 10 minutes, stirring constantly. Remove from the heat and sprinkle the gelatin over the mixture. Whisk until the gelatin dissolves, then stir in the vanilla extract. Cover and refrigerate for 1 hour.
Beat the egg whites with an electric mixer in a medium-size mixing bowl until soft peaks form. Gradually add 1/4 cup of the granulated sugar and continue to beat until the peaks are stiff. Fold the egg whites into the pumpkin mixture. Spread evenly over the crust and refrigerate for about 2 hours.
With an electric mixer, beat the heavy cream with the remaining 1/2 cup sugar until medium peaks form. Stir in the bourbon. Spread the whipped cream evenly over the top of the pie. Garnish with the pecan halves.
Yield: one 9-inch pie; 8 servings