Rinse chicken and pat dry. Season the chicken pieces on all sides with salt,pepper & garlic powder. Heat olive oil in a large skillet on medium heat. Work in batches so pan isn't crowded, place the chicken pieces skin side down in the pan. Cook until browned, about 5 minutes, then turn over and lightly brown the other side. Remove chicken to a platter, set aside. Drain off all but 2 tablespoons of the rendered fat. If you have less than 2 T. of fat in the pan, add more olive oil until you have 2 T.
Add the sliced onions, bell peppers, and mushrooms to the pan. Increase the heat to medium high. Cook until the onions are translucent, and the mushrooms are dry, stirring frequently, about 10 minutes. Add the garlic cook a minute more.
Add the wine and broth,scrape up any browned bits at the bottom of the pan. Simmer until the wine is reduced by half. Add the tomatoes. Stir in salt and pepper to taste and the spices. Taste & adjust seasonings. Simmer uncovered for 5 minutes. Place the chicken on top of the tomatoes and onions, skin side up. Lower the heat and cover the skillet with the lid slightly ajar.
Cook the chicken on a low simmer, turning and basting from time to time. Cook until the thighs are tender, about 40 minutes.