When you layer ice cream, make sure to freeze every layer so that the above layers don't dissolve into the below one and structure remains solid.
Use a springform pan to easily release the cake without disturbing the layers and texture.
Make sure the ice cream is softened and not straight out of the fridge to help make smooth and even layers.
Before topping the cake with ganache, make sure is chilled and not hot as hot ganache can melt ice cream.
Always level each layer with a spatula dipped in hot water for a clean look.