For the Chocolate Base:
In a large bowl, beat the eggs with sugar until foamy.
Add the milk and oil, mixing well.
Sift in the flour, cocoa powder, and baking powder, then fold gently until the batter is smooth and lump-free.
Pour the batter into a 22 cm cake mold lined with parchment paper.
Bake in a preheated static oven at 180°C for 35–40 minutes. Check for doneness with a toothpick.
Let the cake cool completely.

For the Mascarpone Cream:
In a bowl, combine the mascarpone, powdered sugar, cocoa powder, and Nutella.
Whip until smooth, thick, and creamy.
Refrigerate the cream while you prepare the cake layers.

For Assembling the Cake:
Slice the cooled cake into three even layers.
Brush the first layer with milk (or milk and coffee/cocoa mixture).
Spread a generous layer of mascarpone cream over the first cake layer.
Repeat the process for the remaining layers.
Once the final layer is placed, cover the entire cake with the remaining mascarpone cream using a spatula.
Refrigerate until ready to serve.