Step 1

Preheat the oven to 325°F and generously butter a 9 inch springform pan with butter, then dust with cocoa powder. Set aside.

Step 2

In a large microwave safe bowl combine the cubes of  butter and chopped chocolate. Place in the microwave in thirty second intervals, stirring well between each interval. Repeat until completely melted and no clumps of chocolate remain. Set aside to cool slightly.

Step 3

While the chocolate cools, separate the egg whites from the yolks, placing the yolks in a separate bowl and the egg whites in the bowl of a stand mixer fit with the whisk attachment.

Step 4

Beat the egg whites on medium speed, gradually increasing to high as you stream in granulated sugar to aerate the egg whites. Continue beating on high until medium stiff peaks form.

Step 5

While the egg whites are beating, add the yolks one at time into the chocolate and butter mixture, whisking in between each addition. Add the vanilla, salt, and cocoa powder, whisk to combine.

Step 6

Gradually incorporate the whipped egg whites into the chocolate mixture by dropping large spoonfuls at a time into the chocolate mixture and folding to combine. Mix until combined and no streaks of egg whites or cocoa powder remain. Do not over mix.

Step 7

Spoon the batter into the prepared pan, using the back of a spoon or a rubber spatula to spread into an even layer.

Step 8

Bake at 325°F for 45 to 50 minutes or until a knife inserted into the middle comes out clean and the edges of the cake start to pull away from the sides of the pan.

Step 9

Allow to cool completely before removing from the springform pan and serving with whipped cream, raspberries or powdered sugar! Enjoy!