For the cupcakes, preheat the oven to 350 degrees. Mix together the flour, baking soda, baking powder, and salt in a medium bowl.

In a large bowl, cream the butter with the sugar and vanilla.

Add the egg whites, half at a time. The mixture will go from crumbly to soupy.

Add half of the flour mixture and then half of the sour milk to the butter mixture, mixing until well-blended. Repeat with the remaining halves of each. The mixture should now have a normal cake batter consistency.

Stir in the Oreo pieces.

Pour the batter into two cupcake paper-lined cupcake pans (24 cupcakes total). Bake for about 20 minutes, or until a knife inserted in the center comes out clean. Cool completely before frosting.

While you’re waiting for the cupcakes to cool, make the frosting. First, cream together the shortening, butter, and vanilla. Add in the powdered sugar 2 cups at a time. Then, add in the milk, and mix until well-blended. Finally, mix in the Oreo pieces.

Spread on the cupcakes with a knife, or pipe on with a frosting bag.