I would just use a basic vanilla cake base and add crushed Oreos. Same goes with the frosting… simple SMBC or AMBC, add some Oreos and let your mixer do the work. One of my most popular requested flavors is a chocolate cake with an Oreo buttercream filling.
When I make Oreo cupcakes I use a chocolate cake and use a package of Oreo pudding mixed with a cup of whipping cream and 1/2 cup milk and whip it to the right consistency. Then I frost with a cream cheese buttercream.
-- Hot Mama's Cakes ~ www.facebook.com/hotmamascakes