Start with your favorite Chocolate Cupcake. Any chocolate cupcake will do, I normally use HERSHEY'S "Perfectly Chocolate" Chocolate Cake. (It goes well with my cream cheese frosting.)
Make your favorite Buttercream Frosting. Again, any buttercream frosting will do. Once your frosting is made, ground up a bunch of oreo cookies (I used a few handfuls of oreos and threw them in the food processor), and add them to your frosting. Taste your frosting as you add the oreos in order to find the flavor you're looking for. It won't be a very strong oreo flavor, more subtle.
Top off your Oreo Cupcakes with a whole oreo. Yum!
My students loved them, and were very impressed... They saw there was an extra (mine!) and began to persuade me to give it to them... A bunch of lawyers, they'll be!
Happy baking! And happy crafting!