The first rule when its comes to chocolate is that it does not like water. The addition of water to chocolate will cause the chocolate to seize because the sugar in the chocolate is binding with the water and not with the fats. So when it comes to creating unique flavours of chocolate, the ingredients need to be dry to be successful.
The eggnog bar is a great example of how to approach the creation of flavour. In this case there were two ideas; freeze-dry liquid eggnog and grind the flavour into the chocolate, or try to recreate the flavour of the beverage with its ingredient components.
I am not a fan of drinking eggnog but I do like the cocktail version. So the recipe started in the same was as the Old Fashioned bar by soaking the cocoa nibs in rum to infuse that flavour. The nibs soaked for a month before being dried in the oven for the moisture to evaporate. Then I went about making a creamy mylk chocolate that included the two other primary ingredients in eggnog; nutmeg and vanilla. (I always add vanilla to our milk/mylk chocolate blends because I like the unique sweetness and additional flavour that it brings.)
The final formulation was:
rum + mylk chocolate + nutmeg + vanilla
There is often a lot of trial an error that occurs before a bar hits the shelf but it starts with an idea about the flavour I want to create and how I want to create it, and then I construct the test formulation.