Adapted from Baked Explorations
35-40 chocolate sandwich cookies, such as Oreos , crushed
5 tablespoons. butter, melted
For the Flourless Chocolate Cake:
4 tablespoons (1/2 stick) butter
6 ounces semisweet chocolate, chopped
1-2 tablespoons instant espresso powder (I used 1 tablespoon)
1/4 cup coffee, at room temperature
1/4 teaspoon salt
1 tablespoon vanilla
6 eggs, separated, at room temperature
1 cup sugar
For the Chocolate Pudding:
3/4 cup sugar
1/2 cup cocoa powder
1/4 cup cornstarch
1/4 teaspoon salt
4 egg yolks
2 1/2 Cups Whole Milk
3 tablespoons butter
2 teaspoons vanilla
3 ounces semisweet chocolate, chopped
1 1/4 cups whipping cream
1/4 cup powdered sugar
1 teaspoon vanilla
1 envelope Whip-It, optional (this will keep whipped cream from separating if storing it more than a day)
Preheat the oven to 300º. Spray a 9 inch springform pan with nonstick cooking spray. Line the pan with parchment paper and spray the parchment and sides of the pan.
In a food processor, process the cookies to make crumbs. Pour the melted butter over them and mix with a rubber spatula until well combined.
Pour crumbs into the prepared pan and press it into the bottom and up the sides, leaving about 1/2 inch between the top of the crust and the top of the pan. Press with spoon or fingers to get an even distribution. Freeze for about 10 minutes. Bake for 10 minutes then cool on wire rack.
Make the Flourless Chocolate Cake:
Increase the oven temperature to 350º.
Gently melt the butter and chocolate together in the microwave, stopping to stir at 30 second increments, till smooth. Set aside to cool.
In a small bowl, combine espresso powder, coffee, salt and vanilla. Set aside.
In the bowl of a standing mixer fitted with the whisk attachment, beat the egg yolks with 1/2 cup sugar until the mixture is light and has almost doubled in volume, about 5 minutes. Add the chocolate mixture and beat until just combined. Scrape down the sides and bottom of the bowl and mix on low for a few seconds. Add the coffee mixture and beat until just combined. Scrape down the bottom and sides of the bowl and mix on low for 5 seconds.
In a clean bowl fitted with the cleaned whisk attachment, beat the egg whites until foamy. Gradually increase the speed to high and add the remaining 1/2 cup sugar, beating until soft peaks form.
Mix 1 cup of the egg whites into the chocolate mixture. Use a rubber spatula to gently fold in the egg whites. Add the remaining egg whites and continue folding until they are almost completely combined. Do not overmix. Pour the batter onto the cooled cookie crust and bake for 38 to 42 minutes. Cake should be set but still jiggly in the center. Transfer to a wire rack and cool completely. Cake will sink as it cools. Wrap and refrigerate the cake for at least three hours or overnight.
Make the Pudding:
In a saucepan, whisk together the sugar, cocoa powder, cornstarch, and salt. Add the egg yolks and mix until combined. Slowly pour in the milk, whisking constantly.
In a saucepan over medium heat, bring the mixture to a boil, whisking constantly. Boil for 30 seconds, then transfer it to a medium bowl. Add the butter, vanilla, and chocolate and whisk until combined. Continue to whisk for a few minutes more to cool the mixture slightly. Let the pudding stand for 15 minutes at room temperature. Press a piece of plastic wrap directly onto the surface of the pudding, and chill it for at least 3 hours.
To Assemble the Mississippi Mud Pie:
Whisk the pudding, then pour it onto the top of the cake, staying inside the cookie crust border. Spread evenly. Return the cake to the refrigerator for at least 30 minutes while you prepare the whipped cream topping. Whip cream with sugar, vanilla and Whip-It, if using, to form soft peaks. Spread the whipped cream across the pudding layer, all the way to the sides. Remove sides of the springform and serve. Store leftovers in the refrigerator, up to 2 days.