Simply take ice cream sandwiches and layer them
into a cake pan- and spread vanilla or which ever flavor
ice cream you prefer around it and decorate it as
you would a regular cake.
If you don't need to make a full cake-
you can also take 2-3 ice cream sandwiches
(depending on how many layers you'd like)
and make a smaller cake.
Lay 1 ice cream sandwich on the middle of some
aluminum foil (make sure the foil will be large enough
to wrap around all 2-3 ice cream sandwich plus more.)
Layer some ice cream on top of the ice cream sandwich
with a spoon or a spatula followed by your favorite topping
of oreos, m&ms, crushed nuts, etc... and of course
your 2nd ice cream sandwich and then another layer of
ice cream etc... After all your layers are done fold the aluminum
foil completely around the ice cream sandwich cake folding it
into a rectangle so the ice cream plus ice cream sandwiches
becomes one solid rectangle as it freezes up nicely together
into a nice rectangle of cold sandwiches- cake!
When you're ready to eat it, you can slice it like you would
a cake and you have layers that were easily created with
the ice cream sandwiches.