This is probably a long shot, but thought I'd give this a try.
When I was small, my family went frequently to a restaurant in Minneapolis called Chez Paul. This was in the 80s. I know that it has been closed for some time now.
We always ordered the dark/white chocolate terrine with pistachio sauce. I believe it was voted best dessert by Mpls/St. Paul magazine. I would LOVE to make this dessert at home. If not this exact version, if anyone has something similar, let me know. Thank you!