Reheat oven to 350 degrees F (175 degrees C). Grease and flour 2 9-inch cake pans.
Mix the brownie mix, vegetable oil, water, and eggs in a mixing bowl; mix well with a spoon until thickened and soft, about 1 minute. Spread the batter into the prepared cake pans.
Roast in the preheated oven until set and browned, about 30 minutes. A toothpick inserted into the middle of a pan should come out with moist crumbs. Allow to cool for 10 minutes in pans before removing to end cooling on racks.
After brownies are cool, take out ice cream from freezer and allow softening for about 10 minutes. In the meantime, pour sweetened condensed milk into a saucepan, and merge in the chocolate chips; heat over low heat, stirring constantly, just until chips have melted and the sauce is smooth. Take away from heat and allow cooling to barely warm temperature.
Place one of the layers of brownies into the bottom of a 9-inch springform pan. Consistently spread the ice cream in a layer over the brownies; pour and spread half the chocolate sauce over the ice cream. Top with the other brownie layer, and drizzle the remaining sauce over the top. Freeze until ready to eat, at least 1 hour. Provide topped with whipped topping, if desired.