Oh the dreaded chocolate fan. No way to permanently stop it, but you can use the Bubblegum Troll powerup to stop it from generating chocolate and remove what’s already in play. If by any chance you are able to get pieces that will allow you to match one of the locked pieces go for it, but it’s unlikely. The chocolate can’t advance through locked pieces or spinners, but you still need 105 pieces so you will be resorting to striped candies as usual. If you can remove the piece of chocolate on top of the chocolate machine (while you still have the locked pieces, the chocolate won’t generate. Keep an eye on how many pieces of each you need as one usually ends up needing a lot more.
Thanks to Matthew Dean
Patricia Frederick’s Tips for Candy Crush Level 156
Keep the candies locked as long as possible to keep the chocolate contained. A few special candies should help complete the orders.