I would cut off the brown parts, unless the color is part of the variety. If it's and indication of oxidation, aging, I'd use something fresh.

...not just slice it, if you want a stronger garlic flavor.

A blender or food processor is a good idea. Make a nice paste.

Bon appetite.

It's done. Took 2-3 hours of mashing in a large mortar and pestle.

The garlic was fine. However, I think I should have purchased new pignoli (pine nuts). I used the ones in the frig, but they were more than six months old. I ruefully discern a certain bitterness.

No, I'm not going to throw it out.

I had pesto last night on basil linguini. It was great! I use a food processor. It doesn’t take any time, and I get the nuts more like ground than paste, which is how my mother in law taught me to make and like it. She also used walnuts and more parsley than basil. But for her it was because she had walnut trees!

However black garlic is delicious as a spread - like fig jam. (I don't think useful for cooking.)
https://en.wikipedia.org/wiki/Black_garlic