For my son Jeffrey's 16th birthday, I made him an ice cream cake.  It was really easy.  I purchased a package of Oreos, a gallon of cookies and cream ice cream, and a tub of whipped cream (Cool Whip).  I took one package (row) of Oreos and crushed them in my food chopper.  Then I mixed them with 1/4 cup melted butter and put them on the bottom of a spring form pan to make the crust.  I packed it pretty well then stuck it in the freezer for a few minutes.  I then took the ice cream (melting) and put it on top of the crust.   I let that sit in the freezer for a minutes also.  Then I covered the top in Cool Whip and added a few crushed Oreos to the top.  I froze it for a few hours.  To serve, I took it out of the freezer for 5 minutes, ran a knife (dipped in hot water) around the edges, then released it from the spring form pan.  You could add in layers of Oreos, chocolate syrup, cake or whipped cream if you have time to let every layer freeze/melt.  I didn't have that much time, but it turned out great anyway!  I also made one in a holiday plastic tub and gave it to my friend Holly.  You could also use a store bought Oreo pie crust and make an ice cream pie.  I just wanted the leftover Oreos!