Preheat your oven to 180°C (350°F). Grease and lightly flour a round cake pan to prevent sticking and ensure easy release once baked.
In a heatproof bowl, melt the dark chocolate and butter together using a double boiler or in short microwave intervals, stirring until smooth and glossy. Let it cool slightly before adding to the batter.
In a separate bowl, whisk the eggs and sugar together for several minutes until the mixture becomes pale and airy — this step helps create a lighter texture in the cake.
Gradually fold in the melted chocolate mixture, ensuring it is well incorporated without deflating the batter.
Add the flour, baking powder, and salt, mixing gently until just combined to avoid overworking the batter.
Pour the batter into the prepared pan, spreading it evenly. Bake for 25–30 minutes, or until a toothpick inserted in the center comes out clean. The cake should be firm to the touch but still moist inside.
Allow the cake to cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely before assembling.
2. Prepare the Caramel Peanut Filling:
In a heavy-bottomed saucepan, melt the sugar over medium heat without stirring until it becomes a deep amber color. Swirl the pan occasionally to prevent burning.
Carefully pour in the warm cream in a thin stream while stirring constantly — the mixture will bubble vigorously, so proceed with caution.
Once the bubbling subsides, add the salted butter and stir until the caramel is smooth and fully blended.
Remove from heat and let it cool slightly. Stir in the roasted peanuts, roughly chopped if you prefer a crunchier texture. Allow the caramel to thicken to a spreadable consistency before using.
