chocolate sandwich cookies

From the martha stewart show:

Chocolate sandwich cookies
6 T butter
3/4 c pow sug
3/4 c flour
Cocoa (how much)
1/8 t salt
1 egg
1/2 t vanilla

Shape into rectangle
Chill
Roll out w/ rubber bands on rolling pin
Cut out w/ rectangle cutter
Bake 325 for 12-14min

6 T unsalted butter
2 c pow sug
1 drop food coloring
2 drops peppermint