Step 1

Preheat your oven to 350F.

Step 2

Butter a 9-inch springform pan

Step 3

In a food processor, grind the chocolate wafters until they become fine crumbs. You'll want 1 1/2 cups of crumbs total, this was just exactly 24 Nabisco chocolate wafters for me. If you want to save a little for dusting on top of the final pie like I did, you can add one or two more and reserve a tablespoon or so.

Step 4

Add the crumbs to the melted butter and stir together until evenly incorporated.

Step 5

Press the crumbs into the bottom of the prepared springform pan, and up the sides a little bit (about 1/2 inch). Using a flat-bottomed measuring cup to tamp them down is an easy way to get a nice, even layer.

Step 6

Bake the crust for 5 minutes in the preheated oven. Remove and set aside.

Step 7

Heat 1 cup of heavy whipping cream over medium or medium-high heat until it just begins to boil.

Step 8

Take the cream off the heat and add the chopped chocolate, salt, and vanilla extract.

Step 9

Allow to sit for 10 minutes or so until the chocolate is completely melted. Stir until everything is evenly mixed.

Step 10

Set the ganache aside to cool at room temperature, or place in the fridge once it’s cooled down a bit.

Step 11

Whip 2 cups of heavy whipping cream and the sugar until medium-stiff peaks form. You don’t want to over beat it, but you want the peaks to stand up on their own without flopping over.

Step 12

Gently fold the room temperature ganache into the whipped cream until completely mixed, and there are no streaks.

Step 13

Pour the mousse into the springform pan, and spread out evenly. You can shake the pan a bit to get it to even out a little more, but you don’t want to knock too much of the air out of the mousse.

Step 14

Refrigerate overnight, or at least 6 hours.

Step 15

To garnish, whip 1 cup of heavy whipping cream and spread in the middle of the cake. Top with cocoa powder or extra chocolate cookie crumbs.