In a large skillet preheat the olive oil or butter.
In a bag add the flour and then add the thighs and shake until the thighs are coated.
Place the thighs in the skillet and brown, but do overcook as they will cook later.
In a large 15x9 pan (lasagna pan) add the thighs and cover - set aside.
Prepare the stuffing according to the package directions, but do not cook - set aside.
To the skillet, add the diced celery and onions. Cook until they start to caramelize. Remove and add to the thighs in the lasagna pan. Re-cover the pan and set aside.
To the skillet add the wine, mushrooms and spinach. Reduce heat and simmer until the spinach just begins to wilt. Add this mixture to the thigh pan.
Prepare the chicken gravy and cover the thighs in the lasagna pan.
Spread the prepared stuffing mix over the dish and sprinkle with grated Swiss cheese.
When ready to eat, heat the mixture in a 350º oven for 35 minutes.