In a large bowl, whisk the egg yolks with half of the granulated sugar until well blended.

In another bowl, mix the buttermilk, olive oil, and vanilla extract together. Gradually add the oil while whisking.

In a separate bowl, combine the cake flour, baking powder, baking soda, and kosher salt.

Slowly incorporate the dry ingredients into the wet mixture, stirring until smooth.

In a clean bowl, beat the egg whites with cream of tartar and a pinch of salt until foamy.

Gradually add the remaining sugar while continuing to beat until firm peaks form.

Gently fold the egg whites into the yolk mixture in three additions, being careful not to deflate the batter.

Spread the batter evenly in a greased half sheet tray and bake at 350°F for 18-20 minutes, or until golden brown and springy to the touch.

Allow the cake to cool completely on a wire rack before cutting it into layers.

For the filling, steep the milk with coffee beans and vanilla, then strain the mixture.

In a bowl, whisk together the cornstarch and sugar, then temper with the hot milk mixture before cooking on the stove until thickened.

Remove from heat and stir in the softened gelatin until it dissolves. Let it cool slightly before folding in the Italian meringue.

To prepare the meringue, cook sugar and water to 238°F, then stream it into the whipped egg whites until glossy and firm peaks form.

Fold the meringue into the cooled pastry cream until fully combined.

Assemble the cake by cutting layers from the cooled sponge, soaking them with a mixture of olive oil and espresso, and layering with the filling in between.

Wrap the assembled cake in plastic wrap and refrigerate for at least 6 hours, preferably overnight, to set.

Unwrap the cake, invert it onto a serving platter, and frost with the mascarpone frosting made from mascarpone, cream cheese, butter, and powdered sugar.