Steps

• Let’s prepare the batter by starting to beat the 3 egg yolks with 3 tablespoons of boiling water, 1/3 cup of sugar, and a pinch of salt with an electric mixer until we have a fluffy and frothy mixture. With a spatula, fold in the sifted flour with cornstarch, vanillin, and baking powder, and mix well from the bottom up. Beat the egg whites until stiff peaks form in a squeaky clean glass or ceramic bowl, using clean beaters, because even the slightest bit of fat might prevent them from whipping properly. Gradually add the remaining sugar while continuing to whip until we get a full, white meringue.

  When the egg whites are well beaten, fold them into the egg yolk mixture, mixing from bottom to top. When the batter is ready, pour it into a 12×16-inch baking pan lined with parchment paper

  

• Bake in the oven at 375°F for about 12 minutes. While the roll is in the oven, prepare a clean kitchen towel with plenty of powdered sugar. When the roll is cooked, flip it onto the towel, remove the parchment paper, and, starting from the short side, roll it up together with the towel. Let it cool wrapped in this way on a wire rack.

  

• In a bowl, mix the chestnut jam with the rum and fold in the whipped cream using the electric mixer. Mix until a homogeneous mixture is obtained. When the filling is ready, unroll the cake and spread the cream, leaving a couple of inches free only on the short side farthest from you. Roll the cake over the cream. Place it in the fridge for an hour and then arrange it on a serving tray or plate, sprinkle with powdered sugar, and decorate with dark chocolate melted in a double boiler. Serve it sliced or whole to be cut at the table!