I've got to try this, thanks for sharing!
I will marinate the mushroom caps first, perhaps some Worcestershire sauce.
Years ago, I got a steak side dish recipe in Santa Fe called "Southwestern Shrooms" which calls for marinating the mushrooms in burgundy, then seasoning them with chili and cumin powder and sauteeing with shallots in butter an olive oil. I'll bet that would work well with what you've done.