Preheat your oven to 350°F (175°C) and prepare two round baking pans by greasing them with butter and dusting with flour.

Mix egg yolks and caster sugar together in a mixing bowl until it reaches a creamy and pale consistency.

Incorporate lemon zest, fresh lemon juice, and melted salted butter into the egg mixture.

Combine buttermilk and extra virgin olive oil into the mixture.

Add vanilla extract and whole eggs, stirring until the mixture is smooth and velvety.

Whisk together brown sugar, caster sugar, plain flour, cocoa powder, baking powder, baking soda, and sea salt in a separate bowl.

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

Blend in hot coffee until the batter is smooth.

Pour the batter evenly into the prepared baking pans and bake for about 25 minutes, or until a toothpick comes out clean.

Cool the cakes completely in the pans for about 10 minutes before transferring them to a wire rack.

Beat cream cheese and vanilla bean paste or extract until smooth in a mixing bowl.

Add lemon zest and pure icing sugar, mixing until well combined.

Fold in the mascarpone until the mixture is creamy and luscious.

Assemble the cake by placing one layer on your serving plate, spreading a generous amount of filling in between, and topping it with the second layer.

Frost the outside of the cake with the remaining filling.

Dust the top with dark cocoa powder for decoration.