Preheat the oven to 350ºF. Spray a 9-inch springform pan with cooking spray.

Prepare the cake batter according to the package directions. Pour the batter into the prepared pan and bake according to directions or until a toothpick inserted in the center comes out clean and the cake springs back when lightly touched. Let cool completely. Remove the cake from the pan. If the top of the cake has a dome, cut it off with a long serrated knife to make it flat. Then slice the cake in half horizontally. Clean the pan and place one half of the cake back in the pan.

Remove the ice cream from the freezer and let it soften for 5 minutes or until it can be spread easily but is not melted. Spread the ice cream on top of the cake layer in the pan and top with the other half of the cake. Freeze the cake for at least 2 hours or until the ice cream has frozen solid again.

To make the chocolate ganache, place the chocolate chips in a heat-proof bowl. Pour the cream into a small saucepan and bring just to a boil. Pour the cream over the chocolate and let sit for 5 minutes. Whisk until the chocolate is smooth and glossy. Let cool for a few minutes.

Remove the cake from the pan and place it on a wire rack placed over a baking sheet. Pour the chocolate ganache on top of the cake and, with an offset spatula, spread it evenly over the top, letting some of the chocolate drip down the sides. Return the cake to the freezer until ready to serve.