You can only copyright the recipe part if you sell it in a bottle - example is
the recipe for Coca Cola. However if the drink is sold as something that is
made up at a bar, a coffee shop or an ice cream shop etcetera, (made up on the
spot) than you register the name only. A certificate is not an official
registration you have to do it on the state level (which is a small area) or
the Federal level which covers a whole country. It is better on the Federal
level.