Ingredients
Equipment
Method
- Preheat and Prep: Preheat your oven to 350°F (175°C). Butter a 9x13-inch baking pan really well, right into the corners.
- Make the Quick Buttermilk: Stir the 1 teaspoon lemon juice into the 2 cups milk and let it sit for 5 minutes while you get everything else ready. It'll look slightly curdled — that's exactly what you want.
- Whisk the Dry Ingredients: In a large bowl, whisk together the flour, cocoa powder, instant coffee, baking soda, baking powder, and salt. Whisk for a good 30 seconds so the coffee and leaveners are evenly distributed. (WATCH VIDEO BELOW)
- Whisk the Wet Ingredients: In a separate bowl, whisk the eggs and brown sugar until smooth, then whisk in the milk mixture, oil, and vanilla.
- Combine: Sift the dry ingredients into the wet and whisk gently just until you don't see any dry streaks. Do not overmix — a few small lumps are totally fine and will bake out. The batter will be on the thin side, and that's what makes this cake so moist. (WATCH VIDEO BELOW)
- Bake the Cake: Pour the batter into the prepared pan and bake for 35–40 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.
- Cool and Poke: Let the cake cool in the pan for about 20 minutes — warm, not hot. Using a skewer or the round handle of a wooden spoon, poke holes all over the cake, about ½ inch apart, going most of the way down. (WATCH VIDEO BELOW)
- Make the Nutella Soak: In a microwave-safe bowl, heat the heavy cream until just steaming and bubbling around the edges, about 45 seconds. Stir in the 1 cup Nutella and the pinch of salt until completely smooth and glossy.
- Soak the Cake: Pour the mixture evenly over the warm cake, working in a slow zigzag so it seeps into the holes, then spread it across the surface with an offset spatula. Let it sit for a few minutes to soak in. (WATCH VIDEO BELOW)
- Melt the Chocolate: In another microwave-safe bowl, melt the chocolate chips in 20-second increments until partially melted. Add the butter and continue in 20-second bursts, stirring between each, until combined and completely smooth.
- Coat the Cornflakes: Add the crushed cornflakes in increments, folding gently after each addition until every piece is evenly coated. Be gentle — you're keeping those shards intact. (WATCH VIDEO BELOW)
- Assemble & Serve: Spoon the chocolate cornflake mixture evenly over the cake and gently spread it into an even layer, all the way to the edges. Let it set for about 15 minutes, then slice. Serve warm with a scoop of cold vanilla ice cream!
Poke the holes while the cake is warm, not hot and not cold. This is the single biggest thing I've figured out from making this cake year after year. At 20 minutes of cooling, the crumb is set enough to hold the holes but still warm enough to absorb the Nutella soak. Too hot and the holes collapse; fully cooled and the soak just sits on top and never sinks in.
Add the butter to the chocolate after it's partially melted. Melting them together makes the chocolate more likely to seize. Partially melt the chocolate first, then stir in the butter and finish in short bursts.
Crush the cornflakes with your hands, not a food processor. You want big, irregular shards — that's where the crunch comes from. A processor turns them into sand and you lose the whole point of the cake.
Nutrition
Notes
Storage
- Room temperature: Loosely cover the pan with foil and keep at cool room temperature for up to 2 days. This is the best way to store it — the crunch layer stays crunchiest here.
- Fridge: Up to 4 days in an airtight container, but know that the cornflakes will soften into more of a chewy, fudgy layer. Still delicious, just different!
- Reheat: Microwave a single slice for 15–20 seconds — just enough to warm the cake and loosen the Nutella soak. Don't go longer or the chocolate topping gets messy.
- To bring back the crunch: Warm a slice in a 300°F oven for 5 minutes, uncovered. It re-crisps the topping surprisingly well.
- Freezer: Freeze the cake base only (before the soak and topping) wrapped tightly for up to 2 months. Avoid freezing the finished cake — the cornflake layer thaws soggy.