The player is required to score at least 600 points per second (180,000 points / 300 seconds = 600 points per second).
This level's board is not very big, and the locked chocolate confines things even more.
Even when all the locked chocolate is gone, there is a chocolate spawner that the player will have to attend to lest its chocolate being spread again is desired.
The presence of four candy colors makes it easier to create special candies and trigger cascades.
Strategy[]
Use combinations to plow through the locked chocolate and then keep the chocolate spawner at bay as you rack up your score.