Preheat oven to 375 degrees. In a medium bowl, mix the cookie crumbs, sugar, and melted butter with a fork. If you are going to use cookie crumbs to garnish the pie, set aside a few tablespoons of the mixture.

Press the remaining mixture into a 9-inch pie pan, covering the bottom and sides of the pan, going as high as you can up the edge, making a small edge or rim. Bake for 8 minutes and then cool on a rack while you prepare the filling.

In a deep 2-quart saucepan, mix together the egg yolks, water, sugar, salt, and water with a fork. Add the chocolate squares and the gelatin over the top of the mixture. Cook on medium heat, stirring until the gelatin dissolves and all the chocolate is melted. Remove from heat and stir in the vanilla.

Pour chocolate mixture into a large bowl. With a hand mixer at high speed, beat for one minute. The mixture may look a little speckled (like malt) but that's okay. Chill in the fridge, stirring every 15 minutes, for about 45 minutes.

With a handheld mixer at high speed, beat egg whites and the cream of tarter until soft peaks form. Turn the mixer on high and gradually add in 1/4 sugar until the peaks are stiff. Set aside.

Take the chilled chocolate mixture and beat it until fluffy, about 2 minutes. Use a wire whisk to gently fold in the egg whites until well combined. Pour the mixture into the piecrust and refrigerate for 3 hours.

Just before serving: With a handheld mixer or in the bowl of a standing mixer, beat the whipping cream at high speed until medium-stiff peaks form, adding a little sugar at a time. Taste the whipped cream and adjust the sugar (add a little more if you like) depending upon your desired sweetness. Spread loosely over the pie. Garnish with chocolate shavings (if desired) and the reserved cookie crumbs (optional).