To make the filling, place the chocolate in a large microwave-safe bowl and microwave on high in 30 second increments, stirring after each, until melted and smooth. Or place the chocolate in a heat-proof bowl over a pot of simmering water on the stove top and over medium heat, melt until smooth, stirring periodically. Let cool to room temperature.
In the bowl of a stand mixer fitted with the paddle attachment, mix together the cream cheese, brown sugar and salt, on medium-high speed, until smooth, scraping down the bowl with a rubber spatula as needed.
On low speed, add the yolks, one at a time, and then the 1 tablespoon vanilla, and beat until smooth, then continue beating for about 5 minutes.
Add the cooled chocolate to the cream cheese filling and mix on medium until combined.
Place the whites in a large bowl and using a hand mixer, beat on medium speed until foamy. If you do not have a hand mixer, transfer the chocolate filling from the stand mixer bowl to a large mixing bowl, clean the stand mixer bowl and use it and the whisk attachment to whip the egg whites. Add the granulated sugar in a slow and steady stream, increase the speed to high, and whisk the whites until stiff peaks form. Gently fold the whites into the filling with a rubber spatula.
In the bowl you just whisked the whites in, no need to clean it, whisk 2 cups heavy cream on medium-high until it holds stiff peaks. Gently fold the cream into the filling.
Transfer the filling to the Diamond Nuts Walnut Crust, smoothing the top with an offset spatula. Place in the freezer until frozen, abut 5 hours, or overnight.
About 30 minutes before you are ready to serve the pie, remove it from the disposable pie tin and let rest at room temperature. Right before serving, whip the remaining cup of heavy cream and the remaining 2 teaspoons vanilla until soft peaks form and spread the cream over the top of the pie. Sprinkle with toasted and chopped Diamond Nuts walnuts. Dip a knife into hot water for the prettiest slices.
The pie will keep in the freezer tightly wrapped in plastic wrap for up to a week.