Preheat your oven to 180°C (350°F). Grease your baking pan with a little oil and line the bottom with parchment paper for easy removal later.
In a large mixing bowl, crack the eggs and add 200g of sugar. Using an electric mixer, whisk together until pale and fluffy (about 5-7 minutes).
Pour in the 50ml of oil and add the 1 tbsp of vanilla essence. Mix until well combined.
In a separate bowl, sift together the 250g of flour, 60g of cocoa powder, and 1 sachet of baking powder. Gradually fold the dry ingredients into the wet mixture using a spatula.
Pour the batter into the prepared baking pan, smoothing the top with a spatula. Bake for 25-30 minutes, or until a toothpick inserted comes out clean. Let it cool for 10 minutes before transferring to a cooling rack.
In a mixing bowl, add the 500g of mascarpone and 150g of sugar. Beat with an electric mixer until creamy. In another bowl, whip the 300ml of whipping cream with 1 tbsp of vanilla essence until soft peaks form. Gently fold the whipped cream into the mascarpone mixture.
Once the cake is completely cool, slice it into two equal halves horizontally. Spread half of the filling over the first half, then place the second half on top and spread the remaining filling over it.
Refrigerate the assembled cake for at least 2 hours to allow the flavors to meld and the filling to set. Dust with cocoa powder or icing sugar before serving.
