Puree raspberries in a food processor. Press raspberry mixture through a wire-mesh sieve, using the back of a spoon to squeeze out juice. Discard seeds. Bring juice to a boil over high heat; cook over medium heat, stirring often, until mixture is reduced to 1/2 cup. Remove from heat, and cool completely.
Butter an 8" round cakepan, and line bottom with wax paper.
Cook water and sugar in a saucepan over medium heat until sugar dissolves, stirring occasionally. Add butter, and cook, stirring occasionally, until butter melts. Remove from heat, and add chocolate; stir until smooth. Cool.
Whisk together raspberry reduction, eggs, flour, and almond extract in a large bowl. Add chocolate mixture, and beat at medium speed with an electric mixer until blended. Pour into prepared cakepan.
Place cakepan in a larger pan; add hot water to large pan to a depth of 1". Bake at 325° for 42 to 45 minutes. Remove from water bath. Cool cake completely in pan on a wire rack.
Run a thin knife around pan to loosen cake. Invert cake onto a platter; remove wax paper, and invert onto another platter.
Cut cake into wedges, and serve with sweetened whipped cream and fresh berries, if desired.
Make-Ahead Plan: If desired, cake can be made a day ahead. Cover and chill in refrigerator; let stand at room temperature at least 1 hour before serving.