Preparation

• Half an hour before baking, preheat the oven to 170 ºC so it reaches the right temperature when you finish preparing the batter.
• Melt the butter in a saucepan over low heat or in the microwave in short intervals to prevent burning.
• Once the butter is melted, add the crumbled chocolate. Stir constantly until the chocolate completely melts and the mixture is smooth. Incorporate half of the sugar and continue stirring until it's fully dissolved.
• Next, gradually add the sifted flour to the butter and chocolate mixture while stirring constantly with a spatula or whisk to prevent lumps from forming.
• Separate the egg whites from the yolks, ensuring no yolk gets into the whites (the yolks are not used in this cake).
• Beat the egg whites to stiff peaks using an electric mixer. When they begin to rise, incorporate the remaining sugar and continue beating until the whites are firm and glossy.
• Gently fold the egg whites into the batter, using a spatula with upward and over motions to retain the air and lightness of the mixture.
• Incorporate the chopped walnuts, stirring gently with the spatula until they are well distributed throughout the batter.
• Grease a mold with butter and lightly flour it to prevent the batter from sticking. Fill the mold with the prepared batter and let it rest for a few minutes to stabilize.
• Bake at a temperature of 170 ºC for about 50 minutes, or until when inserting a toothpick into the cake, it comes out clean.
• Allow the cake to cool for about 10-15 minutes in the pan and then unmold it onto a wire rack until it cools completely.