I made this and it was just as fantastic as described!
Love it, and will make it again!
I used bone-in chicken thighs (2 1/2 pounds), skin removed.
I used green Spanish olives, and I really think you can use whatever olives you like. I will use kalamata next time if I have some.
I used fresh mushrooms, sliced, and that was great.
I will note that my standard packet of dry chicken gravy mix weighed .87 ounces, not 1.25 ounces, so I used that and it worked out just fine. There is plenty of seasoning, and no need for additional salt with the salty olives, etc.
At the end, I thinkened the sauce just a tad with some cornstarch, removed the chicken from the bone, and served the whole shebang over rice. Adults loved it, kids not so much, but that's OK with me. It's a pretty sophisticated flavor, that wine.