This is obtained in the Sunny Beach level in Summer Forest however you need to buy the climbing ability from Moneybags in Autumn Plains first for 500 gems.
Towards the end of the level there is a ladder you can climb that will take you to a chef who tells you he's going to make the turtles into soup but is offering you a chance to save them.
All you need to do is herd the turtles into the water to save them but the key factor is that you headbutt them so they will ricochet off the walls and (hopefully) go into the water but you can hit them again to finish the job.
The best part f this (imo) is that it isn't a top-down view like the original which made this MUCH easier; just keep running laps around the cauldron and headbutting any turtles you see. Be warned, though, that they don't bounce as much as they did in the original so you might need a few retries
There are two rounds of this game, each rewarding you with an orb.