Before you do anything else - get yourself a set of these silicone mats:
https://www.amazon.com/s?k=Bright+Kitchen
They have one to fit whatever dehydrator you use; round Nesco's, cabinet Excaliburs, LEMs, Cosoris...
LOVE them. Made drying the eggs easy peasy
AND - I'll be using them to dry up tomato puree into flakes, stocks and broths from my kitchen, and who knows what else LOL
Inor - you could easily dry the milk you need for your chocolate project.
This vid is about drying broth - but there's excellent info about drying liquids in general.