1. Start by making the ganache. Place chocolate into a medium bowl. Heat cream in a small saucepan over medium heat. Bring cream just to a boil, then immediately pour over the chopped chocolate, and whisk until smooth. Let cool slightly before using.
2. Heat oven to 350 degrees. In double boiler, melt remaining chocolate and butter over low heat.
3. In medium bowl, whisk together eggs and granulated sugar until combined.
4. Fold melted chocolate mixture into egg mixture. Pour into a round 9-inch cake pan.
5. Set pan in a larger pan, then add water to the larger pan so it comes about halfway up the side of pan to make a water bath. Bake for 25 to 30 minutes or until it appears dry on the top and no longer jiggles.
6. When done, remove from oven and cool completely in pan. When cool, flip out of pan onto a cake board and then onto a wire rack.
7. If necessary, gently heat ganache until it is slightly warm and pourable. It cannot be hot. Pour over cake and cover completely. Let set just until firm, about 45 minutes.
8. Whip cream with powdered sugar and vanilla and beat until stiff peaks form.
9. Garnish each cake slice with a dollop of whipped cream and a piece of fresh fruit.