Preheat oven to 350 degree F. In large bowl, combine cake mix, Kahlua, coffee, eggs, and oil. Beat on low speed to blend, then beat on medium for 2 minutes more.

Divide evenly between 2 greased and floured round baking pans. They do not have to be torte pans. Bake for 30 to 35 minutes, or until cake tester comes out clean. While cakes are baking, prepare Chocolate Mousse Filling. In small bowl, beat egg yolks on high speed until thick (about 3 minutes). Gradually beat in sugar. In medium saucepan, heat one cup whipping cream over medium heat just until hot (do not boil). Slowly stir some of the heated whipping cream into the egg and sugar mixture, then stir it back into the cream in the saucepan. Cook over low heat for 5 minutes, stirring constantly, until mixture is thickened. (Do not bring to a boil.) Add the chocolate chips and stir until melted. Remove from heat. Cover and refrigerate until chilled, about 1 to 1 and 1/2 hours. When cakes are baked, cool in pans on cooling rack for 10 minutes. Remove from pans and cool on racks until completely cool.

While cakes are baking or soon after they come out of the oven, prepare the Chocolate Glaze. In small saucepan, heat whipping cream and chocolate chips over medium heat until chocolate is melted and mixture is smooth (do not boil). Remove from heat and let cool to room temperature.

To assemble cake, slice each cake layer in half horizontally (you will have 4 cake layers) and top first layer with one third of Chocolate Mousse Filling. Top with second cake layer and pour half of the Chocolate Glaze over, letting it run down the sides of the cake. At this point, please refrigerate these layers to set the chocolate and mousse (about an hour). Put another third of mousse over chocolate, and top with third cake layer. Cover third layer with remaining mousse, and refrigerate for another hour to set. Put the fourth cake layer on top. Spoon remaining Chocolate Glaze over the top, letting some of it drip over cake edges. Refrigerate immediately.