Preheat oven to 350 degrees F (175 degrees C). Line bottom of a 10 inch springform pan with parchment paper.
In a heavy saucepan over low heat, or using a double boiler, mix butter or margarine and cola and heat through. Remove the pan from the stove and add chocolate, stirring to melt. Let this mixture cool completely.
In a small mixing bowl, blend raspberry preserves and lemon juice together. In the bowl of an electric mixer, whip the eggs with sugar and vanilla sugar for 10 minutes on high speed. Whisk cooled, melted chocolate into egg mixture until thoroughly incorporated (mixture will deflate but that's OK). Stir in raspberry preserve mixture.
Place the prepared springform pan on a cookie sheet in the oven and reduce the oven's heat to 325 degrees F (165 degrees C). Bake 55 to 60 minutes until the cake is done. The cake is done when the top has a slight crust and seems set. Cake may rise and fall but that is fine. Refrigerate the cake several hours.
To make the glaze: Melt the chocolate chips with butter or margarine in a double boiler; stir to melt evenly. Cool, then pour over chilled cake before serving.