- 10 tablespoons unsalted butter, plus more for the pan
- 6 ounces bittersweet chocolate, chopped
- 1 cup sugar, divided
- 3 large eggs, separated
- ½ teaspoon kosher salt
- 2 teaspoons vanilla extract
- 1 cup all-purpose flour
- 1 packed cup chopped Snickers bars
- cocoa powder, for dusting
- Heat the oven to 325°F. Butter a 9-inch springform pan with removable sides. Set a heatproof bowl over a pot of barely simmering water. Add the butter and the chocolate to the bowl and heat until melted and smooth, stirring occasionally, about 5 minutes. Remove the butter mixture from the heat. Let cool slightly.
- Whisk 3/4 cup of the sugar into the butter mixture until smooth. Whisk in the egg yolks, salt, and vanilla. Fold in the flour.
- In a clean bowl, beat the egg whites with an electric mixer on medium until they are light and foamy. Add the remaining 1/4 cup sugar and beat until stiff peaks form, about 3 minutes. Stir about 1/3 of the egg whites into the chocolate batter, then gently fold in the remaining whites.
- Transfer the batter to the prepared pan and smooth the top. Sprinkle with the Snickers bars. Bake until a toothpick inserted into the center of the cake comes out with moist crumbs attached, 30 to 35 minutes. Transfer cake to a rack to cool completely. To serve, remove the pan sides and dust with cocoa powder.