Peanut Butter Whoopie Pie cookies

Yum.
Fast track from 2010 when I made Whoopie Pie cookies for the 1st time.
I am now on the Whoopie Pie course.  I can't stop thinking of them, or baking them.
I want everyone to try them.  They look divine and they taste heavenly.

I make them for a friend who has just come back home after living abroad  and she is wondering where these have been all her life.  She too, is in love.   :)

I want all of my friends to join in the fun.  I decide on making her the Peanut Butter Whoopie.

I use the original chocolate cake recipe for the Whoopies from "Joy Of Baking"
http://www.joyofbaking.com/WhoopiePies.html

and the Peanut Butter Filling from "Martha Stewart".
http://www.marthastewart.com/312753/peanut-butter-buttercream

Peanut Butter Whoopie Pie cookies

Cake:   1  3/4 cups all-purpose flour
            3/4 cup Dutch-process cocoa powder
            1 tsp baking powder
            1/4 tsp baking soda
            3/4 cup butter, room temperature
            3/4 cup granulated sugar
            1 large egg, room temperature
            1 tsp pure vanilla extract
            1/4 cup buttermilk
            1/2 cup strong coffee, lukewarm

*Preheat oven 375F.  Line your baking sheets with Sil-Pat or with parchment paper.
(or you can use a Whoopie Pie pan.  If using, grease the pan).
*In a large bowl, sift flour, cocoa powder, baking powder and baking soda.
*In another bowl, beat butter and sugar until fluffy and light.
*Add the egg, beating well.
*Beat in the vanilla extract.
*Using another bowl, stir in the buttermilk and coffee.
*With the mixer on low,  alternately add the flour mixture and buttermilk/coffee mixture, in 3 additions.  Beginning and ending with flour.
*Drop the batter using either a Tablespoon or teaspoon (to make smaller rounds) or a small ice-cream scooper onto the baking sheets.  Place 1  1/2 inches apart (they spread).
(IF using the Whoopie Pie Pan, drop a Tablespoon in the greased with butter).
*Bake for approx. 10 minutes or until when lightly pressed the tops of the cookies spring back.
*Transfer to a cooling rack.

Filling:   2/3 cup peanut butter
               1/2 cup (1-stick or 8 Tbsps) butter, softened
               3/4 cup confectioners' sugar

*Using a paddle attachment, cream peanut butter and butter on high speed.
*On low speed, mix sugar, until combined.
*Then change to high speed again, and beat mixture until fluffy and smooth.
**Use immediately.

***Take one cookie, on the flat-side spread a heaping Tablespoon or pipe the filling on the cookie.
Top with another cookie.

***Please Note: I use Salted Butter, then I do NOT use the salt requested in the recipe.