Step 1

Preheat the oven to 325°F.

Step 2

Make the cake: In a large bowl, whisk together the egg yolks, ¾ cup cold water, olive oil, vanilla paste, and ¾ cup of the sugar until well combined. In a separate bowl, sift together the flour, baking powder, and salt. Mix the flour mixture into the egg yolk mixture, carefully folding with a spatula until well incorporated.

Step 3

In a stand mixer with the whisk, whip the egg whites, cream of tartar, and lemon zest on medium-high until very frothy and thickened, 2 to 3 minutes. Gradually add the remaining ¾ cup sugar, little by little, to incorporate it into the egg whites. Keep whipping the eggs until they’re slightly shiny, have some volume, and just barely hold their shape (soft peaks), about 2 minutes.

Step 4

Remove the bowl from the mixer and add the egg yolk/flour mixture little by little, folding with a rubber spatula, until very well combined.

Step 5

Pour the batter into an ungreased 9 × 13-inch baking pan. Bake until a knife inserted into the center comes out clean, 35 to 45 minutes. Cool upside down, in the pan, on a wire rack. (This will help the cake retain its height.)

Step 6

Meanwhile, make the soaking liquid: In a large bowl, stir together whole milk, condensed milk, evaporated milk, olive oil, vanilla paste, salt, and lemon zest. Set aside.

Step 7

Once the cake is cool, carefully run an offset spatula or butter knife around the sides of the pan to release the cake from the sides, but leave the cake in the pan.

Step 8

Poke holes all across the surface of the cake with a cake tester or toothpick and pour the milk mixture slowly and evenly over the top (it may take a few minutes for the mixture to soak all the way in). Cover the cake and refrigerate overnight.

Step 9

Just before serving, make the mascarpone topping: In a stand mixer with the whisk, whip the heavy cream on medium-high speed until thickened and it just barely holds its shape, about 2 minutes. Add the mascarpone, vanilla paste, sugar, and salt and whip briefly to combine.

Step 10

Spread all of the topping across the top of the cake with an offset spatula or the back of a large spoon.

Step 11

To serve, slice the cake into roughly 3-inch squares. Drizzle with the olive oil and top with lemon zest. Leftovers keep, tightly sealed in the refrigerator, for up to 3 days.