Q. For Shabbat we prepare an essence of tea to be able to drink tea. Do we need to do the same with instant coffee or cocoa?
A. Igros Moshe, (O.H. 4:74,16) rules that since instant coffee is prepared by roasting the coffee beans, which are then ground and brewed. This is followed by the cooked beans being spray dried with hot air to remove all of the moisture from the beans. Both the cooking and the spray drying procedure renders the coffee powder as completely cooked and the rule of Ein Bishul Achar Bishul (there is no cooking of the same item twice) applies. See also Shemiras Shabbos K’ (1: 55).
The commonly accepted Minhag for many, is to be a bit more stringent, and pour hot water from the kettle into a cup (Keli Sheini) and from that cup into another that contains the instant coffee in it.
If the cocoa powder is produced in a similar fashion, the same would apply.
Horav Shlomo Miller’s Shlit’a opinion is similar.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller, Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a