Whoopie

To prepare the whoopies, start by adding a teaspoon of lemon juice to the fresh liquid cream 1 (if you have buttermilk, go directly to step 2). Add the vanilla extract to the mixture 2 and stir. Beat the room temperature butter together with the sugar 3 using a mixer (or a stand mixer) until you get a light and fluffy mixture.

While still beating, add the room temperature egg 4, the salt, and the cream and lemon mixture (or buttermilk) with the vanilla 5. In a separate bowl, sift the flour and cocoa 6,

add the baking powder 7 and mix all the dry ingredients with a whisk 8. Now gently incorporate them into the butter, sugar, and egg mixture 9,

alternating with the room temperature milk 10. You should get a rather dense mixture which you'll place in a pastry bag with a smooth nozzle about 3/4 inch in diameter. Squeeze mounds of about 1 1/2 inches in diameter 11 onto a baking tray lined with parchment paper (you should get rather tall semi-spheres) for a total of about 16 mounds per tray 12. Bake in a preheated static oven at 350°F for about 13-14 minutes, then remove the whoopies from the oven and transfer them to a wire rack using a steel spatula. Let the whoopies cool.

In the meantime, prepare the marshmallow cream by dissolving the granulated sugar in water in a small saucepan; when the syrup comes to a boil, let it cook over medium heat for at least 5 minutes. Meanwhile, in a large bowl, beat the egg whites with a pinch of salt 13 until stiff peaks form, and when the 5 minutes have passed, add the hot sugar syrup in a thin stream while continuing to beat. Continue until the mixture is lukewarm. Then incorporate the vanilla 14 and the powdered sugar 15.

The whoopie cream should be dense, smooth, and glossy (16-17). Transfer it to a pastry bag with a smooth nozzle and squeeze the cream onto the flat side of a cookie 18 and cover with the flat side of another cookie. Continue in this way until all the ingredients are used up.