Instructions

1. Heat the oven to 325°F. Coat 2 (9-inch) round cake pans with cooking spray. Line the bottom of each with a parchment paper round.
2. Whisk 1 cup granulated sugar, 2/3 cup neutral oil, 1/2 cup sour cream, 1/3 cup packed light brown sugar, 2 large eggs, 1 teaspoon vanilla extract, and 1/2 teaspoon kosher salt together in a large bowl until smooth.
3. Sift 1 1/2 cups all-purpose flour, 2/3 cup Dutch-processed cocoa powder, 1 teaspoon baking powder, and 1/2 teaspoon baking soda into the bowl and whisk until just combined. (The batter will be thick and lumpy.) Whisk in 2/3 cup hot brewed coffee until smooth. Divide the batter between the pans (about 2 cups or 18 ounces each).
4. Bake until a tester inserted into the center of the cakes comes out clean, 18 to 20 minutes.
5. Place the pans on a wire rack and let cool slightly, about 10 minutes. Run a small offset spatula or paring knife around each cake to loosen. Flip the cakes out of their pans, remove the parchment, and place on the rack. Let cool completely, at least 1 hour.
6. Use a serrated knife to trim the domed tops off of the cooled cakes (you can save the scraps for snacking) and loosely cover to keep from drying out.
7. Assemble a 9-inch springform pan. Line the inside of the pan with a sheet of food-grade acetate to make a collar that’s about 3 1/2 inches high when measured from the bottom of the pan. Tape the collar to seal. Place one layer of cake cut-side up in the pan. (Alternatively, the cake can be assembled freeform on a plate or cake stand with several layers of acetate tightly wrapped around the first layer of cake.)
8. Microwave 3 ounces coarsely chopped bittersweet chocolate in a medium microwave-safe bowl in 30-second increments, stirring between each, until just melted, 60 to 90 seconds total. Let cool slightly, then stir in 1/8 teaspoon instant espresso powder if using.
9. Beat 3 ounces room-temperature cubed cream cheese, 1/2 cup powdered sugar, 3/4 teaspoon vanilla extract, and 1 pinch kosher salt together in a stand mixer with the whisk attachment, starting on low speed and increasing to medium speed, until combined and smooth, scraping the sides of the bowl with a flexible spatula as needed, 1 to 3 minutes.
10. With the mixer still running, slowly pour in 3/4 cup cold heavy cream and beat, continuing to scrape as needed, until soft peaks form, 2 to 4 minutes.
11. Fold the cream mixture a spoonful at a time into the chocolate mixture, making sure the cream is completely incorporated between each addition, until smooth and combined.
12. Transfer onto the first layer of cake and smooth into an even layer with a small offset spatula, going all the way to the edges. Freeze while you prepare the white chocolate cream.
13. Wash and dry the stand mixer bowl and whisk attachment.
14. Microwave 2 ounces coarsely chopped white chocolate in a small microwave-safe bowl in 20-second increments, stirring between each, until just melted, 40 to 60 seconds total. Let cool slightly.
15. Beat 3 ounces room-temperature cubed cream cheese, 1/2 cup powdered sugar, 3/4 teaspoon vanilla extract, and 1 pinch kosher salt together in the stand mixer with the whisk attachment, starting on low speed and increasing to medium speed, until combined and smooth, scraping the sides of the bowl with a flexible spatula as needed, about 1 minute.
16. With the mixer still running, slowly pour in 3/4 cup cold heavy cream and beat, continuing to scrape as needed, until stiff peaks form, 2 to 4 minutes.
17. Stir a spoonful of the cream mixture into the white chocolate to lighten. Add the white chocolate mixture to the stand mixer and beat on low speed until smooth and just combined, 45 seconds to 1 minute.
18. Transfer onto the dark chocolate layer and smooth into an even layer. Freeze until the white chocolate cream is firm enough to hold up the top layer of cake, about 30 minutes.
19. Place the top layer of cake, flattest side up, over the white chocolate cream layer, and gently press down. Refrigerate while you make the ganache.
20. Microwave 1/3 cup heavy cream in a small microwave-safe bowl until very hot and bubbling, about 45 seconds. Add 2 ounces coarsely chopped bittersweet chocolate, making sure the chocolate is submerged. Let sit for 1 minute. Stir until the chocolate is fully melted and the ganache is smooth.
21. Pour the ganache over the top of the cake and nudge it with the back of a spoon or offset spatula into an even layer.
22. Refrigerate until well-chilled and set, at least 6 hours and up to overnight.
23. When ready to serve, remove the ring from the springform pan and peel the acetate collar away from the cake. If the cream isn’t as smooth as you’d like, you can use a hot, dry small offset spatula to smooth out those areas. Decorate the top with white chocolate shavings as desired. For the cleanest-looking slices, cut the cake with a serrated knife dipped in hot water and wiped dry, and wipe the knife clean between cuts.