Ingredients
Scale
Chocolate Cake
- 2 1/2 cups (300 g) all-purpose flour
- 3/4 cup (64 g) unsweetened cocoa powder
- 2 cups (400 g) granulated sugar
- 2 teaspoons baking powder
- 1 1/2 teaspoons baking soda
- 1/2 teaspoon fine salt
- 3 large eggs, room temperature
- 1 cup (240 ml) whole milk, room temperature
- 1/2 cup (120 ml) neutral vegetable oil
- 2 teaspoons vanilla extract
- 1 cup (240 ml) hot brewed coffee or hot water
Chocolate-Hazelnut Filling
- 1 cup (240 ml) cold heavy whipping cream
- 8 oz (226 g) full-fat cream cheese, softened
- 3/4 cup chocolate-hazelnut spread
- 1/2 cup (60 g) powdered sugar, sifted
Chocolate Buttercream
- 1 1/2 cups (340 g) unsalted butter, softened
- 4 1/2 cups (540 g) powdered sugar, sifted
- 3/4 cup (64 g) unsweetened cocoa powder
- Up to 1/2 cup (120 ml) heavy cream
- 2 teaspoons vanilla extract
- Pinch of fine salt
Chocolate Ganache
- 8 oz (226 g) semi-sweet chocolate, finely chopped
- 3/4 cup (180 ml) heavy cream
Decoration
- 3/4 to 1 cup toasted hazelnuts, whole and halved
- Chocolate-covered hazelnut bites, as needed
- Chocolate wafer pieces, as needed
- Milk chocolate squares, as needed
- Reserved chocolate buttercream
- About 1/2 cup vanilla buttercream
Instructions
- Preheat the oven to 350°F (175°C). Grease two 9-inch square 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.
- In another bowl, whisk the eggs, milk, oil, and vanilla. Add to the dry ingredients and mix just until combined.
- Slowly mix in the hot coffee or hot water. The batter will be relatively thin. This is normal.
- Divide the batter evenly between the prepared pans. Bake for 30–35 minutes, or until a tester inserted near the center comes out without wet batter.
- Cool in the pans for 10–15 minutes. Turn onto cooling racks, remove the parchment, and cool completely.
- For easier cutting, chill the cakes for 30–60 minutes. Using a long serrated knife, split each square cake horizontally to make four layers.
- Make the filling. Whip the cold heavy cream to soft-to-medium peaks. In another bowl, beat the cream cheese until smooth. Beat in the chocolate-hazelnut spread and powdered sugar. Gently fold in the whipped cream. Chill for 15–20 minutes if the filling feels too soft.
- Make the chocolate buttercream. Beat the softened butter until creamy. Gradually add the sifted powdered sugar and cocoa. Add the vanilla, salt, and enough heavy cream to produce a smooth but firm frosting.
- Put the first cake layer on a square cake board. Pipe a chocolate buttercream dam around the edge. Spread chocolate-hazelnut filling inside the dam. Repeat with the remaining layers.
- Chill the stacked cake for 20–30 minutes.
- Apply a thin crumb coat of chocolate buttercream. Chill for another 20–30 minutes.
- Apply the final chocolate buttercream coat. Create subtle horizontal ridges around all four sides with an offset spatula or cake scraper. Chill for at least 30 minutes.
- Make the ganache. Place the chopped chocolate in a heatproof bowl. Heat the cream until steaming and beginning to simmer around the edges. Pour it over the chocolate. Rest for 2 minutes, then stir gently until smooth.
- Let the ganache cool until thick enough to drip slowly. Test one drip on the back of the chilled cake. If it runs straight to the bottom, allow the ganache to cool longer.
- Add ganache around the upper edge, creating drips of different lengths. Spread a thin layer over the top.
- Toast the hazelnuts at 350°F (175°C) for 7–9 minutes. Cool completely.
- Pipe alternating chocolate and vanilla swirls around the top. Decorate with toasted hazelnuts, chocolate-covered hazelnut bites, wafer pieces, and milk chocolate squares.
- Refrigerate until firm. For cleaner slices, cut with a sharp knife warmed in hot water and wiped dry between cuts.
Notes
- Do not cut warm cake layers. Chilled layers are much easier to split.
- The hot coffee strengthens the chocolate flavor but should not make the finished cake taste strongly of coffee.
- Do not add extra flour because the batter appears thin.
- Keep the heavy cream cold before whipping.
- A buttercream dam helps prevent the hazelnut filling from squeezing out.
- Chill the cake before applying ganache.
- Always test one ganache drip before decorating the entire cake.
- Let toasted hazelnuts cool completely before adding them to buttercream.
- Add some wafer pieces shortly before serving if you want them especially crisp.
- Because the filling contains cream cheese and whipped cream, keep the finished cake refrigerated at 40°F (4°C) or below.
- For the reference-photo appearance, keep the decoration abundant and slightly irregular rather than perfectly symmetrical.
- Prep Time: 1 hour 30 minutes
- Additional/Chilling Time: 2 hours 30 minutes
- Cook Time: 30–35 minutes
- Category: Dessert
- Method: Baking
- Cuisine: American