12 ounces bittersweet chocolate, chopped
10 tablespoons unsalted butter, cut into small pieces
5  eggs, at room temperature
1/4 teaspoon kosher salt
1/4 teaspoon vanilla extract
1/8 teaspoon almond extract (optional)
1/2 pint raspberries, divided
 hot water, for baking
 whipped cream, for garnish

Preheat the oven to 375°F. Spray a 9-inch springform pan with nonstick cooking spray. Tightly wrap the outside of the pan with 2 layers of foil.

Place a large metal bowl over a pan of barely simmering water, add the chocolate and butter, and stir until the mixture is smooth. Remove the bowl from the pan and allow the mixture to cool to room temperature.

Meanwhile, whip the eggs, salt, vanilla, and almond extract with an electric mixer on high speed until pale yellow and tripled in volume, about 10 minutes. Fold half the mixture into the chocolate mixture until no egg streaks remain. Gently fold in the remaining egg mixture (do not overmix or the batter will deflate). Pour the batter into the prepared springform pan.

Set aside 1/2 cup of the raspberries for the garnish and sprinkle the remaining raspberries evenly over the batter. Push them into the batter until they are almost submerged.

Place the pan in a large baking dish and transfer to the oven. Carefully pour enough hot water into the baking dish to come halfway up the cake pan. Bake until the top is no longer glossy and the cake pulls away from the side when the pan is tilted slightly, 15 to 20 minutes. (Do not overbake. The cake will still be very soft but will become firmer when refrigerated.) Remove the cake pan from the water and allow it to sit at room temperature until cool. Cover the pan with plastic wrap and refrigerate for at least 8 hours before serving. If you omit this step, the cake will fall apart.

To unmold, dip the bottom of the pan in a bowl of very hot water for 15 seconds and run a thin knife around the edfe of the cake to loosen. Release the springform and shake gently to release the cake. Serve with the whipped cream and remaining raspberries.