1. Roughly chop the chocolate and set it aside. Weigh out the sugar, peanut butter, nuttelex, syrup & salt into the bowl of a stand mixer. Then, using the paddle attachment, mix on low until just combined, scraping well to ensure everything is mixed thoroughly. Add water and mix on low until just combined. The natural peanut butter will separate into solids and oil if you over-mix this dough. For this reason, we only want to mix on the lowest setting of the stand mixer.
2. Mix flour, cocoa, baking soda, and mix with a whisk thoroughly in a separate bowl. Add the dry mixture to the dough, mixing until just incorporated. Add chocolate chunks and mix until just combined.
3. Turn the dough onto a surface and gently knead to ensure there are no streaks of peanut butter and that the chocolate is well distributed.
Portion the cookies to 80 grams each, then shape them into discs, about 6cm in width and 2.5cm in depth.
4. Be sure to chill before baking in the fridge. You can put them in the fridge overnight or the freezer for 2 hours. Once cooled, tightly wrap the cookie dough in plastic wrap. The cookie discs can be stored in the refrigerator for up to a week or in the freezer for up to a month.
5. To bake, preheat oven to 170C. Spread the cookies out on a well on a tray lined with baking paper with room to grow.
6. Sprinkle with flaky salt on top and bake for 6 minutes. Take the tray out and bang sharply on the kitchen bench several times. This encourages the cookies to spread and gives a crackle over the surface.
7. Bake for 4-6 minutes longer, less if you prefer a soft cookie and more if you want a crispier cookie. Bang the tray sharply on the surface again immediately after taking the tray out of the oven. Use a spoon to gently push the edges in to give your cookies a rounder shape.