Step 1

To make the Oreo crust:

Step 2

Butter the bottom and sides of a 9-inch springform pan, then line the bottom with a round of parchment paper and lightly butter top of parchment paper. In a food processor, pulse Oreo cookies until finely ground.

Step 3

Pour into a bowl along with 5 Tbsp melted butter and use a fork to stir until evenly moistened. Pour mixture into prepared springform pan and press into an even layer along bottom and up the sides of the pan, coming within a 1/2-inch of the top of the pan.

Step 4

Preheat oven to 300 degrees and transfer to freezer and chill 10 minutes. Remove from freezer and bake in preheated oven 10 minutes. Remove from oven and allow to cool.

Step 5

For the flourless chocolate cake:

Step 6

Increase oven temperature to 350 degrees. Place 6 oz bittersweet chocolate chips and 1/4 cup butter in a microwave safe bowl. Heat mixture in microwave in 20 second intervals on 50% power, stirring after each interval until melted and smooth, set aside to cool slightly.

Step 7

In liquid measuring cup (used to measure water) whisk together water, 1 Tbsp cocoa powder, salt and 1 Tbsp vanilla until well blended. Set aside. In the bowl of an electric stand mixer fitted with the whisk attachment, whip 6 egg yolks 1/2 cup sugar on medium-high speed until mixture is pale and fluffy and has nearly doubled in volume, about 5 minutes.

Step 8

Add melted chocolate mixture and mix just until combined, then scrape down sides and bottom of bowl and mix on low speed 5 seconds longer. Add water mixture and blend just until combined, then scrape down sides and bottom of bowl and mix 5 seconds longer.

Step 9

In a clean stand mixer bowl, whip egg whites until foamy, then gradually increase speed to high, while slowly adding in 1/2 cup granulated sugar and beat until soft peaks form.

Step 10

Scoop out about 1 cup of the whipped egg white mixture and gently fold into egg yolk/chocolate mixture, just until combined, about 30 seconds. Add in remaining egg white mixture and fold just until nearly combined (don't over-mix). Pour mixture into cooled cookie crust and spread into an even layer.

Step 11

Bake in preheated oven 38 - 42 minutes, until cake edges appear set but center still jiggles slightly (cake may appear under-baked). Transfer to a wire rack to cool completely. Once cool wrap tightly with plastic wrap and refrigerate at least 3 hours or up to overnight.

Step 12

For the chocolate pudding:

Step 13

In a medium saucepan whisk together granulated sugar, cocoa powder, cornstarch and salt. Stir in egg yolks and mix until combined (the texture will be thick). While whisking, slowly pour in milk.

Step 14

Heat mixture over medium heat, and bring to a boil, whisking constantly. Allow mixture to boil for 30 seconds then remove from heat and pour into a bowl. Add butter, chocolate chips and vanilla (I used vanilla bean paste because I ran out of vanilla) and stir until combined (I pressed mine through a fine strainer but that's optional).

Step 15

Allow to rest at room temperature 15 minutes, then cover with plastic wrap pressing directly against the surface of the pudding to prevent a skin from forming. Chill in refrigerator at least 3 hours or overnight.

Step 16

To assemble pie:

Step 17

Remove cake and pudding from refrigerator and stir pudding to loosen, then spread pudding into an even layer over flourless cake, staying within the cookie crust border. Chill in refrigerator 30 minutes.

Step 18

For the sweetened whipped cream:

Step 19

In a mixing bowl, using an electric mixer, whip heavy cream until soft peaks form. Add in 3 Tbsp granulated sugar and whip until stiff peaks form. Remove cake from refrigerator and spread whipped cream in an even layer over top of cake.

Step 20

Remove springform ring and cut into slices. Serve within 3 hours (I found I actually liked the cake just as much the second day, but I wouldn't add the whipped cream until it's within a few hours of being served).