Preheat oven to 350°F. Grease and lightly flour a 10-inch tube pan with nonremovable bottom.
Combine corn syrup, milk and vanilla in a small bowl; set aside. Mix butter and shortening in a large mixer bowl just until combined. Sift flour, sugar, corn starch, baking soda and salt over shortening. Add eggs and half the milk mixture. Mix on low speed of electric mixer to combine. Increase speed to medium and beat 1 minute. Add melted chocolate until blended, then remaining milk mixture; beat 1-1/2 minutes. Pour batter into prepared pan.
Bake 50 to 55 minutes until toothpick inserted in center comes out clean. Cool in pan 15 minutes; remove to wire rack to cool completely, about 1 hour.
To assemble cake: Place cake on a plate, curved side up. Slice off top fourth of cake; set aside. Carefully create a “tunnel” in bottom of cake leaving a 1-inch cake shell. Place shell in freezer for at least 1 hour. Fill tunnel with softened ice cream; replace cake top. Cover and freeze for 3 hours or until firm.
Place chocolate chips, butter and vanilla in a medium bowl. Bring cream and corn syrup to a boil in a small saucepan over medium heat (OR heat to boiling in microwave). Remove from heat; pour over chocolate, butter and vanilla. Cover; let stand several minutes until mixture can be whisked smooth and chocolate has melted completely. Cool until mixture is slightly thickened. Spoon sauce over cake just before serving.
Recipe Note: In a hurry? Use a chocolate or devil’s food cake mix, prepared and baked according to package directions in place of the cake recipe above. Assemble cake as directed.