1 Pound Best quality dark chocolate (I actually used milk chocolate mixed with dark chocolate.)
1 Cup Unsalted butter (Cut into small pieces at room temperature)
6 Large Eggs
Raspberries (Optional) (I covered my torte with raspberries- Rose left hers bare. It is your choice.)
Whipped Cream (Optional) (For serving )
Heat the oven to 425° F or 220° C with a rack in the middle of the oven. Butter an 8-inch springform pan that is at least 2 1/2 inches deep. Line the bottom with parchment paper and butter the parchment. Wrap the outside of the pan with a double layer of heavy duty aluminum foil so that no water can sneak in. You will also need a larger roasting pan or cake pan to serve as a water bath. *If using a larger cake pan, be sure it is a one-piece pan.
Melt the chocolate and butter in a large heatproof metal bowl set over but not touching hot (not simmering) water in a saucepan, or microwave in a microwave-safe bowl in 20 second bursts, stirring between bursts. Set the bowl aside but keep the pan of water on the stove, turning the heat up so that the water simmers.
Set a stand mixer bowl over but not touching the simmering water and heat the eggs, stirring constantly with a whisk, until just warm to the touch. Immediately transfer the bowl to a stand mixer fitted with the whisk attachment. Whisk the eggs on high speed until the eggs triple in volume and are billowy and lighten in color, about 5 minutes. *If using a handheld mixer in a bowl, beat the eggs over the simmering water until they are hot, then transfer the bowl to the counter and beat until the eggs cool down to room temperature, about 5 minutes). Use a large whisk or rubber spatula to fold half of the eggs into the chocolate mixture until almost evenly combined. Fold in the remaining eggs until almost no streaks remain. Use a rubber spatula to finish folding, scraping the bottom to make sure that the heavier chocolate mixture is all mixed in.
Scrape the mixture into the springform pan, smoothing the top, and set it inside the larger pan. Place the larger pan on the oven rack and carefully pour 1 inch (2.5 cm) of hot water into the larger pan. Bake for 5 minutes. Cover the pan loosely with a sheet of buttered aluminum foil and bake for 10 minutes more. The cake will still wobble when moved but shouldn't look sloshy. Remove the cake pan from the water bath and let cool on a rack for about 45 minutes. Cover tightly with plastic wrap and refrigerate until very firm, at least 3 hours.
Once it is very firm, unmold the cake. Gather a serving plate that has at least an 8 inch flat center portion, as well as an 8 inch flat loose bottom of a tart pan or plate, covered with plastic wrap, to help with inverting.
Use a kitchen torch, hair dryer, or hot damp towel to warm the sides of the pan to loosen the torte. Run a thin metal spatula or knife around the edges of the torte and remove the sides of the pan. Gently set the plastic-wrapped plate on top and invert the torte onto it. Heat the bottom of the springform pan, remove it, and then peel off the parchment and invert the torte onto the serving plate.
The torte is the most moussey and delicious served at room temperature, though it is also delicious chilled and keeps very well in the fridge for a week or more. To serve, slice with a thing bladed knife dipped in hot water and wiped dry between each slice. Serve with whipped cream on the side. ** If you want to use raspberries, decorate the top of the torte once it is inverted.