Preheat oven to 350°F. Break graham crackers into a food processor and blitz until you have crumbs. Slowly drizzle butter into food processor while pulsing, making sure butter is fully incorporated. Pour crumbs into a 9 inch pie pan, pressing firmly into pan to form a crust.

Pour 1/2 cup cold water in a medium saucepan. Add 1/3 cup sugar, salt, and egg yolks. Stir to blend. Heat over low heat and stir until the gelatin dissolves and the mixture thickens (about 2 minutes). DO NOT BOIL. Remove from heat.

Stir the Cognac or brandy and creme de cacao into the mixture. Chill until it starts to mound slightly when nudged with a spoon (about 15 minutes)

Using a whisk attachment on your stand mixer, beat the egg whites on medium high speed (6 on a Kitchen Aid) until stiff (about 3 minutes. Add the remaining 1/3 cup sugar and beat until peaks are firm (about 1 minute more). Fold the meringue into the mixture in the pot.

Whip the cream in the stand mixer with the whisk attachment on medium high until about doubled in volume. Fold into the mixture in the pot.

Turn mixture into the pie crust and chill until mixture firms (at least 2 hours and up to overnight).

Add cream, brandy or cognac, creme de cacao, and powdered sugar to a stand mixer with the whisk attached. Beat on medium high (6 on a Kitchen Aid) and whip until doubled in volume (about 3 minutes).

Pour mixture onto the pie and spread with a spatula until covered.

Top with cacao nibs.