The Chocolate Factory in Candy Crush Saga will be encountered from Level 156 onwards.
One (or more!) take the place of a single sweet,
but are fixed in place (ie: don't "fall").
These chocolate factories (as their name suggests!) create chocolate squares randomly after you make your move.
Here they will only start producing chocolate when one side is exposed by removing cream.
You'll only get ONE piece per go, irrespective of how many factories are on screen (randomly) and like the normal chocolate you won't get any IF you cleared one or more pieces of chocolate as a result of your last swap.
However, where normal chocolate can be totally cleared from the screen by getting rid of every last piece, the factories will create chocolate irrespective of how much is already on screen, even if there is none!