Diplomatica

To prepare the diplomat, first focus on the sponge cake: in a stand mixer (or a bowl with an electric mixer) put the egg yolks, sugar 1, and a pinch of salt, then whip at medium-high speed for about 10 minutes. You should obtain a light and frothy mixture that passes the writing test. At this point, add the flour and potato starch 2, previously sifted. Add them in several batches and mix gently from bottom to top so as not to deflate the mixture 3.

Pour the mixture into a rectangular mold of 14x9 inches, lined with parchment paper 4. Level the surface 5 and bake in a static oven at 320°F for 50 minutes, on the lower rack of the oven 6. Remove from oven and let cool completely.

Meanwhile, prepare the custard: in a pot pour the milk with the vanilla seeds 7 and bring just to the boil. In a bowl, place the egg yolks 8 and sugar 9, mix with a hand whisk without incorporating air.

Add the cornstarch 10 and mix again 11 to obtain a smooth and lump-free mixture. At this point, add the hot milk and stir to combine 12.

Transfer the mixture to a thick-bottomed saucepan 13 and let it thicken over low heat, stirring continuously 14. Pour the cream into a baking dish, cover with plastic wrap in contact 15 and let it cool first to room temperature and then in the refrigerator until ready to use.

Now, take care of the puff pastry: divide the block of puff pastry in half, then roll them out on a lightly floured work surface to form 2 rectangular sheets of 14x9 inches with a thickness of about 1/8 inches 16. Place them on a baking sheet lined with parchment paper and prick them with the tines of a fork 17. Sprinkle the surface with powdered sugar 18 and bake one sheet at a time in a static oven at 347°F for 25-30 minutes, on the lower rack of the oven.

In the meantime, prepare the syrup: in a saucepan, pour the water and sugar 19 and dissolve over medium heat, stirring continuously. Remove the saucepan from the heat, add the rum 20, and stir. Allow to cool completely 21.

Now prepare the diplomat cream: in a bowl pour the cream, add the powdered sugar 22, and whip 23. Take the custard from the refrigerator and mix it with a whisk to soften it. Add the whipped cream and gently mix from bottom to top 34 to incorporate without deflating the mixture. Transfer the cream to a piping bag.

Take the now-cold sponge cake and remove the crust on the surface 25, then trim the edges 26. Place the sponge cake on the puff pastry rectangles and measure to cut off the excess. Now everything is ready to assemble the cake: place the first puff pastry on the serving plate with the side of the powdered sugar facing up. Cover the surface with diplomat cream 27.

Place the sponge cake on top 28 and moisten it with the syrup 29, trying to soak the outer edges as well. Add another layer of diplomat cream 30.

Lay the last puff pastry sheet on the cream with the side of the powdered sugar facing down 31. Dust the surface with powdered sugar 32 and let it rest in the refrigerator for at least an hour before serving. Your diplomat is ready to be served 33!