Heat oven: To 350°F.
…in food processor: Combine flour, cocoa powders, sugar, salt, and baking powder in the work bowl of food processor, pulsing until mixed. Cut butter into chunks and drop into work bowl; run machine until butter disappears into mixture, which will be powdery. Add egg and vanilla and run machine until the dough begins to clump/ball together.
…with an electric mixer: Beat butter and sugar together until combined. Add egg and vanilla and beat until smooth. Add baking powder, salt and cocoa and beat until combined. Add flour and mix just until it disappears.
Shape wafers: Roll dough between 2 large pieces of parchment paper until very, very thin and roughly the size of a half-sheet pan (13×18 inches). Slide onto board, the back of a baking sheet, or large cutting board (parchment paper and all) and place in freezer for 5 minutes, until firm. Once firm, peel back top piece of parchment paper (it should now come off cleanly, pull it back slowly), then lay it loosely back on the sheet of dough. Flip the sheet over and do the same (gently, slowly peel back the second parchment sheet) until the dough is now loose between them.
You can use the rectangles of parchment from the bottom of your baking pans to give you an idea of the sizes you’ll need for each wafer base, but you basically want to cut the sheet of dough in half. Carefully lift each dough halves into a prepared pan. Patch it where needed so that it fully covers the bottom, pressing it with your fingertips into an even layer, and out to the edges if it fell short. It’s fine if it goes up the sides a little — we’ll trim them after it bakes.
Bake wafers: For 10 minutes — they’ll be mostly, but not fully, baked. [Get started on the cheesecake batter while they bake.] Once the wafers are done, if you have any wafer edges that went up the sides of the pan, gently cut them away, which should be easy when they’re hot, but be careful not to cut through the foil. Leave oven on. Enjoy your wafer snacks.
Make cheesecake batter:
…in a food processor: (Yes, this really works.) Wipe the food processor you used for the wafer layer out so that no crumbs remain. Place sugar, then cream cheeses into the work bowl and blend until smooth. Add eggs, one at a time, blending between each, then sour cream and vanilla, blending until smooth. Scrape down bowl and blend another few seconds until smooth.
… with an electric mixer: Beat cream cheese with sugar until fluffy, then beat in eggs, one at a time, until thoroughly mixed, scraping down the sides and bottom of your bowl between each addition. Beat in sour cream and vanilla.
Both methods: Divide cheesecake batter in half, into two bowls. On my scale, each half weighed 565 grams. (I’m sorry I didn’t measure it in cups. Next time!) Slowly drizzle melted chocolate into first half, whisking until fully smooth. Pour batter into first wafer pan — it’s totally fine if it’s still warm/hot from parbaking.
Add espresso powder and molasses (which makes the color magically coffee-like) to the second bowl and whisk until smooth. Pour second half of batter into second prepared pan.
Bake cheesecakes: Bake both pans at the same time, rotating them mid-way because few oven racks are perfectly level, for 15 to 18 minutes, until cheesecake is set but slightly jiggly.
Cool cheesecakes completely: I am always in a rush and let them rest at room temperature on a rack for 5 minutes and then put them in the freezer to quick cool (this takes 15 to 25 minutes, depending on the freezer). You can also cool it over a couple hours in the fridge.
Assemble your layered cheesecake: When cheesecakes are fully cool, carefully pull the foil sling lining the pan onto your counter, taking the cheesecake with it. Gently pull the foil away from the sides of the cheesecakes so that their sides are fully exposed. Next, you want to remove the parchment paper under your coffee cheesecake layer. Use a thin, long offset spatula to run it around under the wafer layer, making sure it isn’t sticking in any places. Slide the parchment paper out carefully. (Usually you would invert your cake layer onto a rack here to remove the parchment, but I don’t think this is a great idea with soft cheesecake!)
Here is the scariest part: Gently begin lifting your coffee cheesecake from the edges with your fingertips until you can slide both hands underneath it, palms up, fingers spread for maximum support. Give it a practice lift up a half-inch, then inch, before taking a deep breath and moving it quickly on top of your chocolate cheesecake layer. The first time, mine broke. I moved the pieces back into place. It was far from perfect but nobody could tell by the time it was assembled.
Dip a sharp serrated knife in hot water — this is the only thing that gives it a passably smooth edge, trust me — and trim the sides of the cheesecake block so that they’re even. Wipe the knife with a towel and dip it again in water between each cut — trust me. Using the same wipe-then-dip knife method every time you cut into this cheesecake, including when you serve it.
Cut your cheesecake block into 3 equal rectangles. Once you’re done trimming, your cheesecake is usually about 7×11 inches and you want to cut it along the longer side, so each third is going to be 3 2/3 inches, but I highly recommend you use a ruler and not eyeball this. Once again, use a thin spatula to carefully separate the bottom layer of the cheesecake block from its parchment paper (you haven’t done this yet for the chocolate layer) before using your hands to lift and stack thirds of the cake into a 6-layer brick-shaped cheesecake. As you’re lifting, if you notice that your cheesecake is thicker on one side than the other (this totally happens due to aforementioned uneven oven racks and is more noticeable because the cake is so thin), simply turn your layer around so that the final stack is relatively flat.
Trim the edges again if needed, so that they are smooth. To smooth them further, I found I could press a piece of parchment paper against each side and gently peel it back (see 12th photo).
To finish: (You’re at the finish line!) Melt chocolate, 3 tablespoons of the cream, and corn syrup together and then whisk until smooth. Whisk in cocoa powder until smooth. I’m using black cocoa here to darken the color of the glaze so it looks better with the cheesecake. You want your final glaze to be thick but pourable. Add the last tablespoon of cream if needed to achieve this. Pour over top of cheesecake and use an spatula to smooth it and also push some over the edges for a drippy effect. Finish with sprinkles and refrigerate until needed.
To serve: Once again, a wet serrated knife makes the cleanest cuts. Thin slices are best because cheesecake is so rich. Leftovers keep in the fridge almost *too* well, heh.