Preheat the oven to 425°F. Grease an 8 inch springform pan and line the bottom of the pan with parchment paper. Wrap the outside of the pan with heavy duty foil.

Combine the butter and chocolate in a large bowl. Place the bowl over a pan of hot water and stir occasionally until the chocolate is completely melted. (You can also melt the chocolate and butter in the microwave if you stop the microwave every 15 to 20 seconds to stir).

Optional step: While the eggs are still in their shells, place them in warm water (about body temperature or slightly warmer) for about 10 minutes. Warm Eggs will beat with a higher volume.

Crack the eggs into a large mixing bowl and whisk until tripled in volume and soft peaks form. This may take 4 to 5 minutes.

Using a wide spatula, fold 1/2 the egg mixture into the chocolate mixture until almost all the streaks are gone. Gently fold in the rest of the eggs until no streaks appear and all the chocolate is blended with the eggs.

Pour the batter into the prepared springform pan and smooth the batter with a spatula.

Place the pan into a larger pan and pour hot water into the larger pan until the springform pan is sitting in about 1 inch of water. Try not to get any water in the springform pan.

Bake for 5 minutes then cover loosely with foil and bake for another 10 minutes.

Remove from the oven, toss the foil, and let the cake cool at room temperature for 40 to 50 minutes. You can leave the cake in the water bath until the water cools down. The cake will look wet and jiggly while it is still warm. After the cake comes to room temperature, cover it with plastic wrap and refrigerate it for 2 to 3 hours until firm.

Run a thin spatula or knife around the sides of the pan and release the ring of the springform pan. Place a plate on top of the cake and invert the cake onto the plate. 

Remove the bottom of the pan from the cake. If the bottom does not come off easily, place a hot rag on the bottom of the pan and it will release like a dream.

Remove the parchment paper then re-invert the cake onto a serving platter.

Serve with whipped cream and raspberry sauce.

Place all the ingredients in a saucepan and cook over medium heat, stirring frequently for 10 to 12 minutes. Push everything through a strainer to remove the seeds.

Store the raspberry sauce in the refrigerator for 10 days or in the freezer for 1 year.