Flourless Chocolate Cake

This cake can be served plain or garnished with the topping of your choice. Some options are: whipped cream, creme fraiche, or high-quality sour cream, custard sauce, a small scoop of ice cream, or some raspberries or raspberry sauce.

7 oz. semisweet or bittersweet chocolate, broken into chunks
1 cup unsalted butter (2 sticks)
4 eggs, separated
1 cup granulated sugar (divided)
1/2 cup unsweetened cocoa (such as Hershey's)
1/8 tsp. salt

Preheat oven to 350 degrees. Grease the sides and bottom of a 10-inch springform pan. Use the pan to trace a circle of parchment or wax paper, cut it out and line the bottom of the pan; grease the paper.

Put the chocolate and butter together in the top of a double boiler and melt over simmering water. (You can make a double boiler by setting a stainless-steel bowl over a saucepan; the two should fit snugly and the bottom of the bowl should not touch the water in the saucepan.) Stir to blend and let cool slightly.

Put the egg yolks into a medium bowl, add about half the sugar and, with an electric mixer, beat until the mixture is light and thick and it forms a ribbon when you lift the beater, 3 to 4 minutes.
Fold the chocolate mixture into the egg yolk mixture, then sprinkle the cocoa powder and salt over the mixture and fold gently until well-blended.

In a separate- and grease-free - bowl, beat the egg whites until they form soft peaks; gradually add the remaining sugar, beating until firm, glossy peaks form.

Add about a quarter of the beaten egg whites to the chocolate-yok mixture and gently fold until blended; carefully fold in the remaining whites, trying to preserve as much volume as possible.
Gently slide the batter into the prepared cake pan. Bake until a wooden pick inserted in the center come out almost clean (you will still see a few moist crumbs)., approximately 40 minutes.

Let the cake cool, in the pan, on a rack for about 10 minutes. Then, run a thin knife around the inside of the pan to release the cake, and unlatch and remove the side of the pan. Let the cake cool completely before cutting; it will be fragile while still warm. As the cake cools, it will collapse like a fallen souffle- that's fine.