Grease the bottom of an 8-inch springform pan; set aside.
Combine chocolate, butter, and milk in a heavy medium saucepan. Cook and stir over low heat until chocolate melts. Remove from heat and cool 20 minutes. Beat eggs and vanilla in a mixing bowl with an electric mixer on low speed until well combined. Add sugar and flour; beat on high speed for 10 minutes. Stir chocolate mixture into egg mixture. Pour into the prepared pan.
Bake in a 325 degree F oven for 35 minutes or until torte is slightly puffed on the outer one-third of the top. (Because this is a dense torte, the center will still appear under baked.)
Cool in pan on a wire rack about 20 minutes. While cooling, the torte may fall about 1/4-inch in the center and may develop a brownie-like, crusty surface. With a knife, carefully loosen the torte from the sides of the pan. Cool completely (about 2 to 3 hours). Remove the sides of the pan. Wrap the torte in foil, and chill for at least 8 hours or up to 2 days. To serve, bring the torte to room temperature.
Melt raspberry jam in a saucepan; cool. Stir in raspberry liqueur, if desired. Spread jam atop torte. To cut, use a knife dipped in hot water. Top each serving with fresh raspberries. Dust the berries with powdered sugar, if desired. Makes 16 servings.