1. Prepare a 9×13 inch cake pan by greasing the sides. Preheat oven to 300°F (148°C).
2. Add all dry ingredients to a large bowl and combine.
3. Add eggs, milk, vegetable oil, 1/2 cup of Kahlua and vanilla to the dry ingredients and mix well.
4. Slowly pour the water into the batter, mixing well and being careful of splashing.
5. Pour the batter into the cake pan and bake for about 40-45 minutes, or until a toothpick comes out with a few crumbs.
6. Remove the cake from the oven and poke holes all over. I use a knife sharpening rod, but you could also use a straw.
7. While the cake is still warm, add the chocolate chips to a medium sized bowl. Set aside.
8. Add the sweetened condensed milk and remaining 1/2 cup of Kahlua to a microwave safe measuring cup. Heat heat the condensed milk and Kahlua until they begin to boil, then pour over the chocolate chips.
9. Whisk the chocolate until smooth, then immediately pour over the cake, spreading it into the holes. Don’t let the mixture sit before pouring it over the cake or it’ll start to thicken and not soak in the holes as well.
10. Set the cake in the fridge to cool and soak.
11. When the cake has cooled, add the ingredients for the whipped cream topping to a large mixer bowl. Whip on high speed until stiff peaks form.
12. Spread the whipped cream evenly over the cake. Top the cake with mini chocolate chips and a drizzle of chocolate sauce, if desired. Refrigerate until ready to serve.