• Gather all the ingredients.
  
• Center a rack in the oven and preheat the oven to 375ºF (190ºC). For a convection oven, reduce cooking temperature by 25ºF (15ºC). Butter an 8-inch (20 cm) baking pan. Dust the inside of the pan with flour and tap out the excess. I recommend using a 6-7 inch (15-18 cm) cake pan for a taller cake than mine.
  
• Line the bottom with parchment paper, butter the paper, dust the paper with flour and tap out the excess.
  
• Combine the flour and cocoa powder and sift, set aside.
  
  
• Cut the chocolate bar into small pieces and set aside.
  
• Set a heatproof bowl over a saucepan of simmering water (140ºF/60ºC) and add the chocolate. Stir occasionally until the chocolate is melted. Make sure not to introduce any oil or moisture to the bowl; otherwise, the chocolate will seize.
  
• Add the coarsely chopped butter and let it melted completely. Transfer the bowl to the counter and let the mixture cool.
  
  
• Separate the cold eggs, putting the whites in a mixer bowl or other large bowl and the yolks in a small bowl.
  
  
• While the chocolate is cooling, place the egg whites in a clean bowl with salt. Working with the whisk attachment of the mixer, beat the egg whites until they are foamy and start adding half of the sugar (90 g) in 2-3 separate additions.
  
• Continue to beat on high speed until stiff peaks form and sugar is dissolved (about 5 min total). To test for stiff peaks, the peaks should stand straight up when you lift up the beaters. The whites should not slide around. Transfer the meringue into a bowl and wash the mixing bowl for next step.
  
  
• In the clean mixing bowl, beat the egg yolks and the rest of the sugar (90g) until creamy and stir in the heavy whipping cream.
  
• With a rubber spatula stir the chocolate mixture into the egg mixture.
  
  
• Then add the flour and cocoa powder into the mixture.
  
  
• Using the spatula, stir about ⅓ of the meringue into the batter, then gently fold in the rest until the color is uniform.
  
• Pour the batter into the pan and give the pan several sharp taps on the counter to bring up any air bubbles that may be trapped in the batter.
  
• Bake the cake at 375ºF (190ºC) for 10 minutes. Then reduce the temperature to 340ºF (170ºC) and bake for 30-35 minutes until a toothpick pulls out moist crumbs when inserted near the center of the cake. Transfer the pan to a cooling rack and let the cake cool completely. As the cake cools, it may deflate a bit.
  
• Run a knife along the edges of the cake and carefully turn the cake over onto a plate or cake stand. Decorate the cake with raspberry and dust the powdered sugar before serving.

To Store

• You can keep the leftovers in an airtight container and store in the refrigerator for up to 3 days or in the freezer for a month.