Ingredients:

  • 8 ounces (225g) bittersweet chocolate (70% cacao), finely chopped
  • 2 tablespoons (30ml) strong brewed coffee or hot water (optional, enhances chocolate flavor)
  • 1 cup (2 sticks, 226g) unsalted butter, cut into cubes, softened
  • ¾ cup (150g) granulated sugar
  • ¼ cup (50g) packed brown sugar (light or dark brown)
  • 6 large eggs, separated
  • ¼ teaspoon cream of tartar
  • Powdered sugar, for dusting (optional)
  • Fresh berries (optional garnish)
  • Whipped cream or vanilla ice cream (optional serving suggestion)

Instructions:

  1. Preheat oven to 325°F (160°C). Grease and line the bottom of the springform pan with parchment paper.
  2. Melt chocolate and butter in a double boiler (or bowl over simmering water), stirring occasionally, until smooth. Remove from heat; stir in coffee (if using). Cool slightly.
  3. In a separate bowl, whisk egg yolks and both sugars until light and pale in color.
  4. Gradually whisk the melted chocolate mixture into the egg yolk mixture until well combined.
  5. In a clean, dry bowl, beat egg whites with cream of tartar until stiff, glossy peaks form.
  6. Gently fold one-third of the egg whites into the chocolate mixture to lighten it. Then, gently fold in the remaining egg whites until just combined. Do not overmix.
  7. Pour batter into prepared springform pan. Bake for 30-35 minutes, or until the edges are set and the center is slightly soft. A toothpick inserted near the center should come out with moist crumbs attached.
  8. Let cool in the pan for 15 minutes before releasing the sides of the springform pan. Cool completely before serving.
  9. Dust with powdered sugar (optional) and serve with fresh berries and whipped cream or ice cream, if desired.