An Ice cream cake is ice cream. A popular form is a three-layer cake, with a layer of ice cream between two layers of cake.
In a typical assembly, the cake component is baked in the normal way, cut to shape if necessary, and then frozen. Ice cream is shaped in a mold as appropriate, and these components are then assembled while frozen. Whipped cream is often used for frosting, as a compliment to the two other textures, and because many typical frostings will not adhere successfully to frozen cake. The whole cake is then kept frozen until prior to serving, when it is allowed to thaw until it can be easily sliced but not so much as to melt the ice cream.