In a saucepan over medium heat, whisk the gelatin into the milk until dissolved. Remove from heat and set aside.
Using a stand or hand mixer, mix the Cool Whip, sour cream, and sugar. In small portions, add the milk and gelatin mixture until you get a smooth, consistent texture.
Thoroughly oil all the sides of a 9-inch cake pan (very important when it comes time to remove the cake!). Place half of the batter into the pan. Refrigerate until the layer hardens (around 30 minutes).
While the first layer is hardening in the fridge, use an electric mixer to add the cacao powder to the second half of the batter. Keep the chocolate custard at room temperature while the other layer is setting.
Carefully apply the cacao mixture on top of the white layer. Place the cake in the fridge to set (about 30 minutes).
Place chocolate chips and whipping cream in a microwave-safe dish. In 30-second intervals, melt the chocolate chips and whipping cream, stirring between each round. Continue the process until the chocolate ganache is smooth. Set aside and let it cool to room temperature.
Remove the cake from the fridge. Using a knife, carefully loosen the edges of the cake. Place the cake upside down on a cake stand and gently remove it from the pan. Spread the chocolate ganache on the top of the cake.
Decorate the cake with berries (or any other fruit of your choice). Allow the cake to set in the refrigerator for 2 hours before you are ready to serve it. Slice and enjoy!