1 ¾cupsall-purpose flour7.9 oz -- or weigh out equivalent White Lily all-purpose
1 ½teaspoonsbaking soda
½teaspoonbaking powder
½teaspoonkosher salt
¾cupunsweetened natural cocoa powder
4tablespoonsunsalted butter, softened
4tablespoonsshortening, or just use more butter
1cuplight brown sugar(7 oz weight)
1teaspoonvanilla
1largeegg at room temperature
1cupbuttermilkroom temperature
Filling:
2sticks unsalted butter, softened(8 oz)
2cupsconfectioners’ sugar
17 oz container marshmallow cream
2teaspoonsgood quality vanilla extract
Instructions
Preheat oven to 350 degrees F. Line two baking sheets with parchment. Don’t use cooking spray or anything very slippery because it might cause the cookies to spread.
Thoroughly mix together flour through cocoa and set aside
Using an electric mixer, beat the butter and shortening until creamy, then add the sugar and beat until well mixed. Beat in the vanilla, then add the egg and beat until fluffy, scraping sides of bowl often.
Add the dry ingredients and the buttermilk alternately, stirring with a heavy duty scraper, until batter is smooth and thick.
Drop batter by generously heaping tablespoons onto baking sheets spacing about 2 inches apart (I usually can fit 12 per sheet on a 13x18 inch tray). Bake one sheet at a time for 12 to 15 minutes or until cookies are puffed, slightly cracked and set. Let cool on baking sheets for about five minutes, then carefully transfer to a wire rack.
FILLING: Beat the butter and sugar together until creamy. Beat in vanilla. Stir in marshmallow cream and beat until fully mixed in. Spoon between cookies. Better yet, put in a piping bag and pipe onto the cookies (much neater results). A heavy duty zipper bag with the bottom corner snipped off will also work.
Wrap the cookies in plastic wrap.
Notes
I like the texture and stability of the filling when a little shortening is combined. All butter is fine, but doesn't hold up quite as well. If you are willing to add a little shortening, even as much as ¼ cup (replacing ¼ cup of the butter, of course) will help. A good ratio seems to be ¾ cup (6 oz) butter and ¼ cup shortening (1.7 oz) shortening. The "oz" is weight. Shortening weighs less water than butter and weighs less per volume amount.For the Irish Cream variation, use the shortening version (¾ cup butter, ¼ cup shortening) and add about 2-3 tablespoons of Irish Cream to the filling.