Preheat the oven to 350 degrees F. Grease and flour a 10 inch springform pan. In a large mixing bowl, combine the cake mix and pudding mix. Mix well. Make a well in the center of the mixture and add the eggs, oil, and water. Mix with a spoon until well blended. Spread the cake batter in the springform pan. Place in the oven and bake at 350 degrees F for 45-50 minutes or until a toothpick inserted in the center comes out clean. Remove the pan from the oven and let cool completely on a wire rack. When cool, remove the cake from the pan and place on a work surface. Slice the top 1-inch of the cake off and set aside. Scoop out the center of the cake, leaving a 1-inch wall around the sides and a 1-inch thick base. Discard the scooped out cake or use for another purpose. In a saucepan over medium heat, whisk together the flour and milk. Cook, stirring constantly, until thick. Remove from the heat and let cool. In a mixing bowl, combine the first measure of shortening, butter, sugar, and vanilla. Beat on high speed with an electric mixer until fluffy. Add the cooled milk mixture and beat for 4 more minutes. Spoon the filling into the middle of the cake and carefully place the top slice back on top of the filling. In the top of a double boiler, combine the remaining shortening, chocolate chips, corn syrup, and water over simmering, not boiling, water. Cook, stirring constantly, until the chocolate is melted and the mixture is smooth. Pour the warm glaze over the cake and spread it evenly to cover the entire surface and sides. Place the cake in the refrigerator until serving time. Store leftovers in a covered container in the refrigerator.