1. In the bowl of the Companion equipped with the Knead/Crush accessory, add the butter and powdered sugar, then set the speed to 8 for 40 seconds.
2. Mix the egg with the vanilla, then add them to the bowl of the robot and set the speed to 8 for 20 seconds.
3. In a bowl, mix the flour with the baking powder and salt, then incorporate it into the previous preparation in 3 parts. First, set the speed to 6 for 10 seconds, then a second time at speed 6 for 10 seconds, and finally at speed 6 for 25 seconds. A ball of dough should form.
4. Place the dough in plastic wrap and refrigerate for one hour.
5. Preheat your oven to 200°C (392°F).
6. On a floured work surface, roll out the dough to a thickness of half a centimeter.
7. Cut out rectangles, then place 2 squares of chocolate in the center and fold the sides over.
8. Place them on a baking sheet lined with parchment paper, then bake at 200°C (392°F) for about 12 minutes (the cooking time may vary by a few minutes depending on your oven).