Cake Decorating Topper

how should i garnish/decorate this cake?

im making an ice cream cake for my friend and its a chocolate cake with cookie dough ice cream. what kind of frosting should i use and what garnish or cake topper should i make to put on the top? i was thinking of shaping some of the cookie dough ice cream into cookies and just putting them on top. what do you guys think? no immature annoying answers please and thank you!
she is turning 20. the ice cream isnt going on the top... like any other ice cream cake, the ice cream goes in the middle of 2 layers of cake. i dont want to change the flavors of the cake or ice cream because that is what she specifically requested, however i decided to use a simple vanilla frosting to contrast with the chocolate for a wierd twist. its not really a "cookie themed cake" its just because the ice cream is cookie dough so i thought cookes. any other creative ideas are welcomed! keep them comming people. its a recatagular sheet cake by the way. thanks!

I don't know what your friend likes such as a favorite character, item, etc.

Since you are using cookie dough ice cream here are cakes that are decorated to look like the cookie monster to stick with the cookie theme:

http://www.coolest-birthday-cakes.com/cookie-monster.html

This site actually has really neat cake ideas.

Sounds like a delicious cake. Good luck!

EDIT: Since you using a simple vanilla icing, which is a good choice. Why not just make some chocolate curls and sprinkle on top with some white piping on the edges. You can also make a nice pretty design (like paisley) with some chocolate icing. Here is a pic - it's a wedding cake, but you can get the idea of what I'm trying to describe:

http://static.squidoo.com/resize/squidoo_images/-1/lens1415079_1229629414black-white-cake.jpg

You can also make sugar paste bows and ribbon and make it look like a wrapped gift. You can use whatever color she likes.

http://www.sweetdreamsgourmetbakery.com/giftcake.JPG

Cake Decorating - Making a Golf Bag Cake Topper