Source

Preheat Oven

  • Preheat oven to 350°F

Special Equipment

  • Stand mixer
  • 8" round cake pan

Ingredients

  • 100 grams (7 tablespoons) unsalted butter softened, plus more for pan
  • 60 grams (½ cup)confectioners’ sugar, sifted, plus more for dusting
  • 113 grams (4 ounces) 70% “top quality” dark chocolate
  • 2 extra-large eggs, separated
  • 20 grams (2 tablespoons) potato or corn starch
  • 40 grams (3 ½ tablespoons) extra or superfine sugar

Preparation

  • Heat oven to 350° F.
  • Butter an 8-inch cake pan. Line bottom with parchment.
  • In a large bowl, using a mixer or by hand, beat the butter with the confectioners’ sugar until smooth and creamy.
  • Melt chocolate in a pan on top of stove.
  • Pour warm chocolate over the butter and sugar mixture and beat until smooth.
  • Whisk in egg yolks one at a time.
  • Stir in starch.
  • Using a stand mixer, beat egg whites until soft peaks form.
  • Gradually beat in superfine sugar and continue beating until firm peaks develop.
  • Fold egg whites into chocolate mixture.
  • Scrape the batter out of the bowl, and spread it in the pan.
  • Bake for 18 minutes.
  • Cake will rise and top will look dry and a little crackly.
  • Remove pan from oven, place on a rack and allow to cool completely, about 2 hours. Cake will sink a bit.
  • Unmold cake, peel off parchment, then invert onto a serving dish so the crackly surface is on top.
  • Generously sift confectioners’ sugar over the top, then serve.