Mississippi Mud Pie
For the Graham Cracker Crust:
- 15 whole graham crackers
- 1/4 cup granulated sugar
- 1/2 teaspoon salt
- 8 tablespoons (1 stick) unsalted butter, melted
For the Brownie Cake:
- 8 tablespoons (1 stick) unsalted butter, cut into pieces
- 6 ounces bittersweet chocolate, chopped
- 1/3 cup dark brown sugar
- 1/3 cup cocoa powder, plus more for dusting
- 1 teaspoon pure vanilla extract
- 3/4 teaspoon salt
- 3 large eggs, separated
- 1/2 cup granulated sugar
- 1/4 cup all-purpose flour
For the Chocolate Custard:
- 4 ounces bittersweet chocolate, chopped
- 2 tablespoons unsalted butter, cut into pieces
- 1/2 cup granulated sugar
- 1/4 teaspoon salt
- 1/4 cup cocoa powder
- 1/4 cup cornstarch
- 2 cups whole milk
- 4 large egg yolks
- 1-1/2 cups cold heavy cream, whipped
- Preheat oven to 325 degrees.
- Prepare the graham cracker crust:
- In a food processor, pulse graham crackers, sugar, salt and butter until combined. Firmly press crumb mixture into bottom and at least 2-1/4 inches up the sides of a 9-inch springform pan. Bake until crust is fragrant and edges are golden, 12 to 14 minutes. Let cool completely on a wire rack.
- Increase oven temperature to 350 degrees.
Prepare the brownie cake:
- In a bowl set over a pot (but not touching it) of barely simmering water, melt together the butter and chocolate. Remove the bowl from the heat and whisk in the dark brown sugar, cocoa powder, vanilla extract and salt. Let cool slightly, then whisk in the 3 large egg yolks.
- In a large bowl, beat the remaining 3 large egg whites with an electric mixer on medium until foamy, about 30 seconds. While mixing, gradually add the granulated sugar in a steady stream. Increase the mixer speed to high and continue to beat until you have stiff peaks, about 3 minutes.
- Using a large rubber spatula, fold the egg-white mixture evenly into the chocolate mixture. Sift the flour evenly over the chocolate mixture and fold it in. Transfer the batter to the prepared crust and smooth the top.
- Bake until a crust has formed over the top, the center is just set and a toothpick inserted 1 inch from the edges comes out with moist crumbs attached, 30 to 35 minutes. The center of the cake, under the crust, should still be very moist and fudgy. Let the cake cool completely, at least 90 minutes.
Prepare the custard:
- Put the chocolate and butter in a medium bowl. Place a fine-mesh sieve over the bowl and set it aside.
- In a medium saucepan, whisk together the sugar, salt, cocoa powder and cornstarch. Add the milk, little by little, continuously whisking to incorporate it fully. Whisk in the egg yolks. Heat the mixture over medium heat, stirring constantly, until it has thickened and just come to a low boil.
- Continue to cook the custard, whisking, for another minute, then immediately pour it into the sieve, pushing it through with a small spatula. Let the custard stand for 1 minute, then whisk it together with the butter and chocolate until smooth.
- Pour the custard over the cooled cake. Cover the custard with plastic wrap or wax paper, making sure to press it gently into the surface of the custard. Chill until the custard has set completely, at least 4 hours and up to overnight.
- Just before serving, remove the ring from the springform pan base and transfer the pie to a serving plate.
- Whip the heavy cream to soft peaks and spoon high dollops over the top of the pie, leaving about a 1-inch border. Dust with cocoa powder.