01 -
Preheat your oven to 180°C (350°F) with a rack in the middle. Grease an 8-inch or 9-inch circular springform pan with butter and dust with flour or unsweetened cocoa powder. Set aside.
02 -
In a medium steel bowl, over a bain-marie, melt the chopped chocolate with the butter. Once melted, set aside to cool for 10-15 minutes.
03 -
In a large mixing bowl, whisk together 100g of sugar with the egg yolks until pale and foamy. While whisking, pour in the melted butter and chocolate. Sprinkle in the cornstarch and whisk to combine.
04 -
In a separate large mixing bowl, beat the egg whites and salt to stiff peaks. Gradually add the remaining 100g of sugar while continuing to beat. Fold about 1/4 of the egg whites into the chocolate mixture with a spatula. Gently fold in the remaining egg whites in three to four additions until the batter is airy and jiggly.
05 -
Pour the batter into the prepared pan. Bake for 25-30 minutes, until the cake looks puffy. The edges should be set, and the center still slightly wobbly. Transfer to a cooling rack; the cake will deflate and wrinkle as it cools. Let cool for at least 15 minutes before removing from the pan.
06 -
Enjoy slightly warm for a melty texture, at room temperature for a soft texture, or chilled for a firmer texture.