Hansel and Gretel were the evil masterminds of the whole plot. They worked with the witch Verushka to fake their kidnapping, so that they could capture Granny and force her to bake the secret chocolate truffles that would magically make them invincible.
Hansel and Gretel eat the magical truffles, which makes them gigantic, and they begin destroying the city. Red, Granny, Wolf and Twitchy the squirrel trick Hansel and Gretel into eating more and more of the magical truffles, which makes them so round and fat that they are helpless and unable to move. Helicopters from the HEA (Happily Ever After agency) carry the harmless, grossly obese Hansel and Gretel to prison.
Thanks Joseph C!