1/2cupunsalted butter, softened to room temperature
1/4cuppacked light brown sugar
1largeegg, at room temperature
1tsppure vanilla extract
For the filling
2 cupspowdered sugar
1/4cupunsalted butter, softened
3 tsp heavy cream
2 tsp vanilla
In a medium bowl, whisk together the dry ingredients (flour, cacao powder, baking soda, and salt). Set aside.
Grab a large stand mixer fitted with a paddle attachment or an electric mixer and cream together the butter and shortening until light and fluffy, about 3 minutes. Scrape down the sides as needed. Add both the granulated sugar and brown sugar and combine until fluffy, another 1-2 minutes. Next, add the egg and extracts and mix until combined. Slowly add in the dry ingredients to the wet.
The batter is thick. Allow this to rest in the fridge for 20 minutes while the oven preheats to 350 degrees.
Line a couple baking sheets with parchment paper.
From the cookie dough, roll the dough into little balls (about 1/2 a size of a cookie scoop or about 2-3 tsp) and place them on a baking sheet 2" apart. Slightly flatten the cookie with your index finger and middle finger - don't completely flatten it, just enough the not be a full ball.
Bake for about 7 minutes (large cookies will need more time). Allow to cool slightly on the baking sheets and transfer to a wire rack.
While the cookies are cooling, make the filling (my favorite!).With an electric mixer or stand mixer, cream together the butter and shortening and slowly add in the powdered sugar. Next, add the fluff, vanilla, and heavy cream. Mix until fluffy and light. There may be extra. I did this on purpose. Because if you're like me....you will eat it with a spoon and know NO ONE IS JUDGING YOU.
Spread a healthy amount of filling on one side of a cookie and place another cookie on top to make a sandwich. These will last 4 days on the counter but won't last that long!