It's an Ingredient for the Rem Sacchras castle key; the "Sweets Key"
- Go to the Chess Cookie Basement
- Go to the east part of the map, there is a path that leads you to the next floor of the basement in which you'll find Toothache Mini Boss
- After defeating the mini boss you will obtain the Meringue.
- At the Chess Cookie basement you'll find Ziggy too, he is at the western part of the basement.