Mississippi Mud Pie (aka Muddy Mississippi Cake)

Chocolate Cookie Crust:

Preheat oven to 300 degrees. Lightly spray bottom and sides of a 10-inch springform pan with cooking spray.

Pulse cookies in a food processor until finely ground (you should have about 3 1/2 cups). Pulse in butter until well combined. Transfer mixture to pan, pressing it evenly into bottom and three-quarters of the way up sides. Freeze 10 minutes. Bake until dry to the touch, 10 to 12 minutes. Transfer to a wire rack; let cool completely.

Flourless Chocolate Cake:

Increase oven temperature to 350 degrees. Place butter and chocolate in a heatproof bowl set over (not in) a pot of simmering water; stir until melted and smooth. Remove from heat. In a small bowl, whisk together coffee, espresso powder, vanilla, and salt.

In the bowl of a mixer fitted with the whisk attachment, beat together egg yolks and 1/2 cup sugar on medium-high speed until pale, thick, and almost doubled in volume, 3 to 4 minutes. Beat in chocolate mixture until just combined. Beat in coffee mixture until just combined. Scrape down sides of bowl, then reduce speed to low and beat until evenly incorporated, about 10 seconds.

In the clean bowl of a mixer fitted with the whisk attachment, beat egg whites on medium speed until foamy, about 1 minute. Increase speed to high and gradually add remaining 1/2 cup sugar, beating until soft peaks form, 2 to 3 minutes more. Gently fold 1 cup egg-white mixture into chocolate mixture with a rubber spatula. Fold in remaining egg-white mixture just until combined (do not overmix). Pour into cooled crust.

Bake until cake is cracked on top and set but still slightly wobbly in center, 40 to 42 minutes (it may not appear completely cooked). Transfer to a wire rack; let cool completely. Cake will deflate in center as it cools. Wrap tightly in plastic; refrigerate at least 3 hours and up to overnight.

Chocolate Pudding:

Whisk together sugar, cocoa, cornstarch, and salt in a medium saucepan. Whisk in egg yolks and milk. Bring to a gentle boil over medium heat, whisking constantly to prevent scorching. Boil 30 seconds, then remove from heat and whisk in butter, vanilla, and chocolate until smooth. Transfer to a bowl; cover with plastic wrap, pressing it directly onto surface to prevent skin from forming. Let cool to room temperature.

Pour pudding on top of cake, spreading to edges of cookie-crust border with an offset spatula. Cover with plastic wrap and refrigerate until cold, at least 3 hours.

Whipped Cream Topping:

In the bowl of a mixer fitted with the whisk attachment, beat cream on medium-high speed until soft peaks form, about 1 minute. Gradually add sugar; beat until stiff peaks form, 1 to 2 minutes more. Top pudding layer with whipped cream, spreading to edges of pan. Unmold cake. Serve immediately, or refrigerate, covered with plastic wrap, up to 2 days.