A kitchen scale is the best method to use to measure the 10 oz wt. of chocolate. Using the best quality dark chocolate you can find (I used Ghirardelli) will only make this cake more delicious. Flourless chocolate cake has a texture very similar to cheesecake and is very rich and decadent, so a little slice will go a long way.
You can change up this recipe by adding chopped nuts, orange zest, or top it with fresh berries.
10 oz wt. good quality dark chocolate, at least 65% cacao
3/4 cup butter, cubed
2 tablespoons hot, strong coffee or espresso
6 large eggs
1/4 cup granulated sugar
2 tablespoons icing (powdered) sugar, optional
Preheat the oven to 325 F.
Coarsely chop the chocolate into small pieces that are relatively the same size. Add the chopped chocolate to a microwave safe bowl. Add the cubed butter and hot coffee to the bowl. Microwave on high for 30 seconds. Stir. Continue to microwave in 30 second intervals until melted, stirring between each. Set aside.
Use a stand mixer fitted with the whisk attachment, or a hand held mixer, to whip the eggs and sugar together until they are lighter in color, foamy, and about doubled in size.
Fold about 1/3 of the egg mixture into the chocolate mixture until incorporated. Add the remaining egg mixture and gently fold until completely incorporated and smooth, but be careful not to over mix and deflate all of the air bubbles.
Pour the batter into a lightly greased 8" spring form pan. Bake for 25 to 30 minutes, or until the center of the cake is very slightly jiggly. Remove from the oven and cool to room temperature on a wire rack. The cake will continue to bake slightly once removed from the oven. Once cooled to room temperature, wrap the pan in plastic wrap and refrigerate for several hours or overnight.
Bring the cake to room temperature and sprinkle with icing (powdered) sugar before serving.