Firmly press the crumb mixture into bottom and up the sides of 9-inch pie plate. Refrigerate until firm, about 20 to 30 minutes. Bake until lightly browned and set, about 10 minutes. Cool while preparing the filling.

In a medium mixing bowl, whisk the egg yolks until blended. Set aside.

In a medium saucepan combine the sugar, salt, cornstarch, flour and nutmeg. Whisk in the eggnog.

Cook the eggnog mixture over medium heat, stirring constantly until it thickens and starts to boil. (This takes about 10-15 minutes) Remove from the heat (leave the stove-top turned on).

While whisking constantly, slowly drizzle about half the hot mixture into the beaten egg yolks. Add the blended egg mixture back into the saucepan with the remaining hot custard. Return to the heat and cook 3-4 minutes more or until very thick and just starting to boil, stirring constantly to prevent scorching. Reduce the heat if needed.

Remove from the heat and blend in the butter, vanilla and rum. Pour the filling into the prepared crust. Cool to room temperature then refrigerate for at least 8 hours, or overnight.

In a large, cold mixing bowl using an electric mixer, beat the cream on medium speed until soft peaks form. Add the powdered sugar and vanilla and beat on high until firm peaks form. Dollop or pipe the whipped cream on top of the pie filling. Garnish with fresh grated nutmeg.