Here is what I did.
I created another cabinet and made it the same width as the cabinet it is attached too, and then made it 1" in depth and flipped it around facing away from the other cabinet (butted them together back to back). I then deleted the drawer, knob, and toe kick. If you want an over hang you can add it to the new cabinet you just created. I did have to mark all cabinets Flat Sides to make it look right.
If you want the slight over hang on the sides you can create just a counter top by... creating a new cabinet and make it 1.5" in Height, then make it 36 floor to top.. you can adjust the width at this point to match the cabinets you are currently working with.
Hope this make sense.