In this blog entry, you can leave comments about your ideas for Wondertart ingredients that the bosses from the base game could have. We can just assume that you'll simply begin with all those ingredients at the beginning of the DLC and just have to fight the "Wondertart ingredient guardians" to get the last ones.
I'd recommend you to write your ideas in the following format:
- Name: The name of the ingredient.
- Boss: The boss you get the ingredient from.
- Appearance: How the ingredient looks like. Writing the appearance of an anthropomorphic version of it is optional.
- Attack: How Chef Saltbaker uses the ingredient during his boss fight. You can choose whatever phase he'll use it in (including the third and fourth), or even make up an additional phase with the attack.
- Any additional entries that you may add are welcome. Just make sure you give it a name in bold like the three above entries.
The only explicit rule I'd include here would be no ingredients for King Dice and the Devil, since giving them ingredients wouldn't make much sense storyline-wise.