Preheat your oven to 350°F (175°C) and grease your baking pans.

In a mixing bowl, vigorously combine the egg yolks and caster sugar until creamy and pale.

Gently fold in the lemon zest, fresh lemon juice, and melted salted butter.

Pour in the buttermilk and olive oil, stirring lightly until smooth.

Incorporate the vanilla extract and whole eggs. Whisk until unified and creamy.

In another bowl, sift together the brown sugar, caster sugar, all-purpose flour, cocoa powder, baking powder, baking soda, and sea salt.

Gradually add the dry ingredients into the wet mixture, stirring gently until just combined.

Add the hot coffee to the batter, mixing carefully until silky and smooth.

Pour the batter evenly into the prepared pans and bake for about 25 minutes.

Allow the cakes to cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.

For the filling, beat the cream cheese and vanilla together until smooth.

Stir in the lemon zest and pure icing sugar until well combined.

Gently fold in the mascarpone until you achieve a rich, creamy consistency.

Layer the cakes by spreading the filling between each layer.

Dust the top of the cake with Dutch-processed cocoa powder.