1. Beat together cake mix, warm water and eggs with electric mixer on medium-high speed until smooth.
2. Pour into a greased and floured 9x13-inch baking pan.
3. Bake at 325 degrees for 30-35 minutes or until tester in center of cake comes out clean.
4. Let cool on wire rack.
5. While cake is baking, prepare topping: In top of double boiler, over simmering water, combile butter, chocolate chips, sweetened condensed milk and corn syrup.
6. Cook over the simmering water, stirring occasionally, until smooth (20-30 minutes).
7. Remove from heat and beat with an electric mixer until smooth.
8. Cut cake into squares and top with a generous spoonful of warm topping.
9. Top each square with a scoop of vanilla ice cream just before serving.
10. Store topping in refrigerator, tightly capped, for up to a few months; freezes well.
11. Reheat in microwave a serving at a time.