How can you make gray or black butter? Soon, I'll be serving garlic bread, but I would like to add something to the garlic-butter, to make it darker (gray or black). It should look like lead.

So far, I've found two ideas:
- add dark olives
- add caviar

I don't like the idea of the olives because it'll be served with scallops in cheese sauce and some mushrooms. I don't think the taste of olives will fit well.
The idea of adding caviar is better, but expensive, or other black fish eggs are not easily available here.
Squid ink is used to make black pasta, no reason it wouldn't work with butter. Good fishmongers should be able to source it for you.