From the kitchen of Stephanie Knewasser.  Mom
heard from her friend Kathy Fitch that if you dunk a
Ritz cracker in mint chocolate, it tastes like a Girl
Scout Thin Mint Cookie.  I wanted to find a recipe to
duplicate the real thing.  I found 4 recipes online.  
They were all similar.  The  main differences were
[1] brown sugar vs no brown sugar [2] milk vs egg
whites vs whole egg [3] chocolate vs cocoa.  This is
my 1st attempt, and everyone gave them 2 thumbs
up (after being refrigerated), but I'd like to try it with
egg whites for comparison sake.  As always, if I can
find a way to improve a recipe, I'll post the changes.
 
Cream:
6 Tbsp butter
2 Tbsp brown sugar
1/2 c sugar
1 tsp vanilla
3 Tbsp milk
Add:
1/4 c + 2 Tbsp cocoa
1 c + 2 Tbsp flour
1/4 tsp baking soda
pinch salt
This makes a thick dough.

On a piece of wax paper, roll the dough into a log.
Wrap wax paper around the log, twisting at the ends.
Refrigerate until dough is firm enough to work with.

Line cookie sheets with parchment.
Using a SHARP knife, slice the dough into thin
wafers.  To prevent square cookies, rotate the log
after every couple slices.

Bake @ 350, 10-12 minutes.
Let set 4 minutes before moving to a rack to cool.
Bake all cookies.

In a double boiler, melt chocolate.
Don't have a double boiler?
Fill a pot 1/3 full with water.
Place a Pyrex bowl on top.
Over low-med heat, melt
1 bag chocolate mint wafers
Using 2 forks, dunk cookie in chocolate, scrape
excess chocolate off & place on wax paper to set.

Store cookies in refrigerator.

Makes 65 2" cookies.
Chocolate Mint Wafers
Use a fork to dunk in melted chocolate.  Use a 2nd fork to scrape off excess.
Roll dough into log.  Wrap in wax paper.  Twist ends closed.
Baked Thin Mints
Use a SHARP knife to slice THIN.
Thin Mint Cookies
"I like her because she smiles at me
and means it."