Ingredients
Scale
Chocolate Cake Layers
- 2½ cups (300 g) all-purpose flour
- ¾ cup (63 g) unsweetened cocoa powder
- 2 cups (400 g) granulated sugar
- 2 tsp baking powder
- 1½ tsp baking soda
- ½ tsp fine salt
- 3 large eggs, room temperature
- 1 cup (240 ml) whole milk, room temperature
- ½ cup (120 ml) neutral vegetable oil
- 2 tsp vanilla extract
- 1 cup (240 ml) hot brewed coffee
Chocolate-Hazelnut Filling
- 1 cup (226 g) unsalted butter, softened
- 1¼ cups creamy chocolate-hazelnut spread
- 3½ cups (about 395 g) powdered sugar
- 1 tsp vanilla extract
- ¼ tsp fine salt
- 4–6 tbsp heavy cream
Chocolate Buttercream
- 1½ cups (340 g) unsalted butter, softened
- 4½ cups (about 510 g) powdered sugar
- ¾ cup (63 g) unsweetened cocoa powder
- 2 tsp vanilla extract
- ½ tsp fine salt
- 6–8 tbsp heavy cream
Chocolate Ganache
- 8 oz (227 g) semisweet chocolate, finely chopped
- ¾ cup (180 ml) heavy cream
Hazelnut Crunch & Decoration
- 1 cup toasted hazelnuts, finely chopped
- 8–10 chocolate-hazelnut truffles
- 6–8 cream-filled chocolate sandwich cookies
- 5–6 chocolate-covered wafer pieces
- 5–6 small chocolate wafer rolls
- 2–3 tbsp chopped chocolate
- Reserved chocolate-hazelnut filling, for piping
Instructions
- Preheat the oven to 350°F (175°C). Grease three 8-inch round cake pans. Line the bottoms with parchment and lightly grease the parchment.
- Whisk the flour, cocoa powder, sugar, baking powder, baking soda, and salt in a large bowl. Break up any cocoa lumps.
- In a separate bowl, whisk the eggs, milk, oil, and vanilla.
- Add the wet mixture to the dry ingredients. Mix on low just until combined.
- Slowly pour in the hot coffee while mixing on low. The finished batter will be quite thin. This is normal.
- Divide the batter evenly between the three pans. For equally sized layers, weigh the filled pans or batter portions.
- Bake for 25–30 minutes. Begin checking at 24–25 minutes. A toothpick inserted in the center should come out clean or with a few moist crumbs, not wet batter.
- Cool in the pans for 10 minutes. Turn onto wire racks, remove the parchment, and cool completely before frosting.
- Make the filling. Beat 1 cup softened butter until creamy. Add the chocolate-hazelnut spread. Gradually beat in 3½ cups powdered sugar, vanilla, and salt. Add heavy cream 1 tablespoon at a time until thick, creamy, and able to hold its shape. Reserve about ¾ cup for decorating.
- Make the buttercream. Beat 1½ cups softened butter for 3–4 minutes. Gradually add the powdered sugar and cocoa. Add vanilla, salt, and 6 tablespoons heavy cream. Beat until fluffy. Add more cream only as needed.
- Level the completely cooled cakes if necessary. Place the first layer on a cake board or serving plate. For extra stability, pipe a buttercream dam around its edge. Add half of the chocolate-hazelnut filling inside the dam.
- Add the second layer and repeat. Place the third layer upside down so its flat bottom forms the top of the cake.
- Cover the cake with a thin crumb coat of chocolate buttercream. Refrigerate for 20–30 minutes.
- Apply the remaining chocolate buttercream over the top and sides. Smooth with a cake scraper while retaining a subtle handmade finish.
- Press the finely chopped toasted hazelnuts around the lower third of the freshly frosted cake. Chill the cake while making the ganache.
- Place chopped semisweet chocolate in a heatproof bowl. Heat ¾ cup heavy cream until steaming. Pour it over the chocolate. Wait 2 minutes, then stir slowly until smooth and glossy.
- Let the ganache cool until it is thick enough to drip slowly. Test one drip on the chilled cake first. If it runs to the bottom immediately, the ganache is still too warm or thin.
- Add irregular drips around the upper edge. Spread a thin layer of ganache across the top.
- Arrange the truffles, broken sandwich cookies, chocolate-covered wafers, and wafer rolls in a concentrated mound across the center. Pipe reserved chocolate-hazelnut filling between the decorations.
- Finish with chopped chocolate and a restrained scattering of toasted hazelnuts. Chill for about 30 minutes to stabilize before slicing.
Notes
- Do not add extra flour because the chocolate batter looks thin.
- All three cake layers must be completely cool before filling.
- Toasting the hazelnuts gives the crunch layer a much stronger flavor.
- A buttercream dam helps prevent the hazelnut filling from squeezing out.
- Chill the crumb-coated cake before final frosting.
- Chill the frosted cake before applying ganache.
- Always make one test drip before covering the cake.
- Add the wafer rolls and cookies close to serving when possible if you want maximum crunch.
- Use a hot, clean, dry knife for neat slices.
- The decorative quantities are intentionally flexible because the final arrangement depends on the size of the cookies, truffles, and wafers.
- Allergen note: Contains wheat/gluten, eggs, milk, and tree nuts. Commercial chocolates, cookies, spreads, and wafers may contain additional allergens. Check their labels.
- Prep Time: 1 hour 15 minutes
- Additional Time: About 1 hour 30 minutes for cooling/chilling
- Cook Time: 25–30 minutes
- Category: Dessert
- Method: Baking
- Cuisine: American-inspired