Turn oven down to 375°F.
Thoroughly dry chicken thighs with paper towels. Season with salt and pepper.
Preheat sauté pan on medium heat.
Melt ghee in hot pan, place seasoned chicken skin side down in pan, sear only skin side until golden and crispy, approximately 5-7 minutes. Do not overcrowd the pan, sear chicken in a couple of rounds.
Remove chicken from pan, and place skin-side up in 9x13 baking dish. Save sauté pan for the next step!
In the same pan, sauté the onions, garlic and tarragon for 3 minutes, stirring constantly. Add mushrooms and cook for 2 more minutes.
Deglaze pan with chicken stock, then add tomatoes.
Add mushroom mixture to baking dish, and bake for 1 hour. Serve with rice or package in reheatable containers for the weeks lunch!