You can use this same Oreo cupcakes recipe, but divide the batter into mini muffin pans instead. Keep in mind, you'll need mini paper liners. Fill each well almost completely full for a nice domed top. Bake at the same oven temperature, but reduce the time by half — about 10-12 minutes total. Instead of full-sized cookies as toppers, cut them into halves or quarters, or use mini Oreo cookies instead.