👨‍🍳 步骤

1. 1

   Preheat oven to 350°F (175°C). Prepare baking sheets by lining them with parchment paper. You can use six 8-inch round pans or one large rectangular pan and cut layers later.

   💡 专业技巧: Ensure parchment paper is well-secured to prevent shifting.
2. 2

   For the cake layers: In a large bowl, whisk egg yolks with half of the confectioners' sugar (137.5g) and vanilla extract until pale and thick. In a separate bowl, beat egg whites with a pinch of salt until soft peaks form, then gradually add the remaining confectioners' sugar (137.5g) and beat until stiff, glossy peaks form.

   💡 专业技巧: Room temperature eggs whip up better.
3. 3

   Gently fold the beaten egg whites into the egg yolk mixture in three additions. Then, carefully fold in the sifted all-purpose flour until just combined. Do not overmix.

   💡 专业技巧: Folding preserves the airiness of the egg whites.
4. 4

   Divide the batter evenly among the prepared baking sheets, spreading thinly. Bake for 8-10 minutes, or until lightly golden and springy to the touch. Let cool slightly on the sheets before inverting onto a wire rack to cool completely.

   💡 专业技巧: Bake one layer at a time if using a single pan, or bake in batches.
5. 5

   For the chocolate buttercream: Cream the softened butter until smooth. Beat in the melted dark chocolate and cocoa powder until well combined. Gradually beat in any remaining confectioners' sugar (if using extra for the buttercream) until the frosting is smooth and spreadable.

   💡 专业技巧: Ensure the butter is at room temperature, not melted, for the best buttercream texture.
6. 6

   Assemble the cake: Place one cake layer on a serving plate. Spread a thin, even layer of chocolate buttercream over it. Repeat with the remaining cake layers and buttercream, ending with a layer of buttercream on top.

   💡 专业技巧: Use an offset spatula for smooth, even spreading.
7. 7

   For the caramel topping: In a saucepan, combine the 150g sugar, water, and lemon juice. Cook over medium-high heat without stirring until the sugar dissolves and turns a deep amber color. Immediately pour onto a parchment-lined baking sheet.

   💡 专业技巧: Watch the caramel closely; it can go from perfectly caramelized to burnt very quickly.
8. 8

   Once the caramel has cooled and hardened, break it into pieces. Arrange these pieces decoratively on top of the cake. If desired, spread the remaining buttercream around the sides of the cake and coat with ground hazelnuts.

   💡 专业技巧: Work quickly with the caramel as it hardens fast.
9. 9

   Chill the cake for at least 1-2 hours before serving to allow the flavors to meld and the cake to set.

   💡 专业技巧: Chilling makes the cake easier to slice cleanly.