Flourless Chocolate Cake

The Stewarts invited us to a "Simple, Fresh, Delicious Cooking Party" at their house a few months ago. It was such a great idea for a party. Each invited couple was assigned to choose a new recipe from the "Simple, Fresh, Delicious" website (it is a cooking show in Canada). You can choose anything in your category, but the rules are that it has to be something new to you, that you've never attempted to make before. Brandon and I were assigned to make a dessert, so we chose to make this flourless chocolate cake. It was a good choice and was enjoyed by all!

Flourless Chocolate Cake:
1 1/2 cups semisweet chocolate chips (or 8 ounces chopped bittersweet chocolate)
6 large egg whites
6 tablespoons unsalted butter, plus more for pan
1/2 cup granulated sugar
6 large egg yolks

Preheat oven to 275°, with rack in center. Butter a 9-inch spring form pan. Place butter and chocolate in large bowl. Microwave in 30-second increments, stirring each time, until melted; cool slightly. Whisk in yolks.
In another bowl, beat egg whites to soft peaks. Gradually add granulated sugar; beat until stiff and glossy. Whisk ¼ of whites into chocolate mixture; gently fold mixture into remaining whites.
Pour into prepared pan; smooth top. Bake until cake pulls away from sides of pan and is just set in center, 45 to 50 minutes. Cool completely on a wire rack. Serve dusted with confectioners’ sugar.