1. Preheat oven to 275 degrees, with rack in center. Butter a 9” springform pan.

2. Place butter and chocolate in large bowl. Microwave in 30-second increments, stirring each time, until melted; cool slightly.

Whisk in yolks.

3. In another bowl, beat egg whites to soft peaks. Gradually add granulated sugar; beat until stiff and glossy.

4. Whisk 1/4 of whites into chocolate mixture; gently fold mixture

into remaining whites. Pour into prepared pan; smooth top.

5. Bake until cake pulls away from sides of pan and is just set in center, 45 to 50 minutes.

6. Cool completely on a wire rack. Serve dusted with confectioners’ sugar.

Serves 10.