- 2 ¼ cups (12 ounces) semi-sweet chocolate, chopped
- 3/4 cup (1 ¼ sticks) unsalted butter, diced
- 5 large eggs
- 1 cup sugar
- 2 teaspoons vanilla extract
- ¼ teaspoon salt
- ¼ cup unsweetened cocoa powder, sifted
- 2 tablespoons water
- 3 tablespoons unsalted butter, room temperature
- 4 ounces semi-sweet chocolate, chopped
- Preheat oven to 300°F, then grease a 9-inch springform pan and line bottom with parchment paper. Lightly grease parchment paper with butter or non-stick spray.
- In a microwave-safe dish, melt semi-sweet chocolate and butter for 2 minutes, stopping every 30 seconds to stir until fully melted. Cool slightly before adding to mixer.
- In a large bowl or mixer, mix together eggs, sugar, vanilla, salt, and 2 tablespoons of water. Beat on medium speed until mixture is foamy and slightly pale.
- Reduce speed and slowly pour in melted chocolate. Once incorporated, add unsweetened cocoa powder and mix until just blended.
- Pour cake batter into pan and bake for 40-45 minutes. Remove from oven and cool on a wire rack.
- Run a knife around edges of pan to help release cake from pan. Use a sharp knife to level cake if you don’t want a domed top. Transfer to serving platter and refrigerate for 2 hours (longer if possible).
- To glaze cake: melt butter and chocolate in a microwave-safe bowl until smooth. Pour warm glaze over chilled cake and use a flat spatula to evenly spread glaze around edges. Refrigerate for 30 minutes to set.
- Bring cake back to room temperature before serving. Use a warm knife to cut slices, cleaning and warming knife between each slice.