Instructions

• Preheat the oven to 180°C / 350°F. Grease a 6 × 6-inch square pan and set it aside.
• Place 1 1/2 cups chocolate chips in a microwave-safe bowl or small saucepan and melt until smooth (microwave in short intervals, stirring between, or melt over low heat), then set aside to cool until warm but not hot.
• Separate the 4 large eggs (room temperature), placing the whites in a large, dry mixing bowl and the yolks in a separate small bowl.
• Using an electric mixer or a whisk, beat the egg whites until medium peaks form (peaks that hold shape but have slightly drooping tips).
• Add the egg yolks to the whipped whites one at a time, beating after each addition until the mixture is glossy and uniform in color.
• Slowly pour the melted chocolate into the egg mixture while gently whisking until the batter is smooth and evenly combined.
• Pour the batter into the prepared pan and smooth the top with a spatula.
• Bake for 28–30 minutes, until the top is set and a toothpick inserted into the center comes out with a few moist crumbs.
• Remove the cake from the oven and let it cool completely in the pan before slicing. If desired, add frosting.