- Preheat oven to 425 degrees.
- Line a 9-inch springform pan with a double layer of wax paper.
- Butter sides and bottom of pan.
- Set aside.
- Melt chocolate and butter in a double boiler (or in a bowl or smaller saucepan placed over a bigger saucepan of gently boiling water).
- Stir until chocolate is melted and mixture is smooth.
- Set aside.
- With your electric mixer, beat eggs, extra yolks and SomerSweet until tripled in volume, about 7 minutes.
- Fold a third of the melted chocolate into egg mixture.
- Fold in remaining chocolate carefully.
- Pour batter into prepared pan.
- Bake for 20 minutes.
- Allow cake to cool completely before refrigerating.
- Refrigerate for at least 3 hours or overnight.
- Run a knife around edge of pan to loosen cake.
- Carefully unmold onto a serving plate and serve.
