Oreos are my favorite store-bought cookie. Here is a "homemade" version, which tastes nothing like the real oreos but are delicious none the less.
2 boxes Devils Food Cake Mix
3/4 cup butter, melted
1 can vanilla frosting (or make your own)
Mix together cake mix, eggs, and butter. Roll dough into 1 inch balls, and place onto a cookie sheet. Bake 375 degrees for 8 minutes. Do not overbake. Allow to cool for 2 minutes before removing to a wire rack. Cool completely. Once cool, Sandwich 2 cookies together with a tablespoon of frosting.