Cream together softened butter with the white sugar and salt in a bowl, until light and fluffy.
Beat in the egg until fully incorporated.
Sieve together the flour, cocoa powder, and baking soda into the mix.
Mix together dry ingredients and wet ingredients, until combined.
Turn the dough out onto your surface and push together into a flat square. Wrap the dough in plastic wrap and refrigerate for at least 1 hour.
Preheat oven to 325˚F (160˚C).
Remove the dough from the fridge, and for ease of rolling out. To roll out the dough, place a half of the dough between two sheets of parchment paper.
Roll the dough between the two sheets of parchment to ¼-inch (½ cm) thickness.
Using a small round cookie cutter.
Cut the dough into individual rounds and place them on a parchment-lined baking sheet, leaving space (1¼ cm) between each cookie.
Bake in a preheated oven for 15 minutes.
Assemble the cookies by spreading a scoop of the O’Sesame Chocolate Twist onto one of the cookies and sandwiching it with another. Give it a light squeeze and scrape any excess off to clear and even out the sides.