Finding recipes in the lab can be made easier:

The scientists will delete anything you put in that won't work in the recipe. Thus, it's advisable to simply put in 4-6 (depending on the type of candy) of the "secret" ingredients and see which one(s) can be used. After this, you can fill the remaining slots with cacao to see which type(s) of cacao can be used with that secret ingredient. Then you can add in a sugar (there is only one recipe that doesn't take sugar). Last, you can experiment with the flavoring, nuts, etc.

This makes pumping out lab recipes very quick and methodical.