Chocolate sandwich cookies

Ingredients:

Cookie

• 2 cups premium flour
• 1 cup cocoa powder + extra for sprinkling
• 1 teaspoon coarse salt
• 1/4 teaspoon of baking soda
• 1 and 1/4 cups unsalted butter, room temperature
• 3/4 cup granulated sugar
• 1 tsp vanilla extract

Filling

• 1 cup unsalted butter, room temperature
• 2 cups powdered sugar
• A pinch of coarse salt

Preparation:

1. Preheat oven to 160°C. Line two baking sheets with parchment paper.
2. Cookie:
   
   In a small bowl, combine the flour, cocoa powder, salt, and baking soda. In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar until light and fluffy. Add the vanilla extract. Mixing on low speed, add the flour mixture and knead until the dough forms a smooth, slightly crumbly texture. Turn the dough out onto a work surface and knead a few times. Divide the dough in half, form into flat discs, wrap each disc in plastic wrap, and refrigerate for an hour (or up to two days).
3. Generously dust your work surface with cocoa powder. Roll out the dough to a 1 cm thickness and cut out 6 cm circles. Transfer them to baking sheets, spacing them 2 cm apart (using an offset spatula will help). Gather up the dough scraps, roll them out, and cut out more circles.
4. Bake the cookies until the tops are no longer shiny, about 20 minutes. Let cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.
5. Filling:
   
   Using a mixer fitted with a paddle attachment, beat the butter with the powdered sugar and salt until smooth. Fill a pastry bag with the filling.
6. Place half the cookies on a plate or work surface. Pipe the filling onto each cookie, then top with the remaining cookie, pressing gently. Refrigerate for a few minutes to allow the filling to set. Enjoy! The cookies can be stored in a tightly sealed container in the refrigerator for up to a week..