In a small bowl, combine the fennel, salt, oregano, basil, crushed red pepper flakes and black pepper. Mix to combine and set aside.
FOR THE ITALIAN BAKED CHICKEN:
Add the onions and fennel to the sheet pan and drizzle with olive oil. Add half of the spice blend to the vegetables and toss to coat with the olive oil and spices. Spread out into a single layer.
Season the chicken thighs with the remaining spice blend on both sides and place the chicken on top of the vegetables. Roast for 20 minutes.
After the 20 minutes, transfer the chicken to another dish. Add the mushrooms, roasted peppers kalamata olives, and capers. In a 2-cup glass measure, add the wine and chicken broth, then stir in the tomatoes and garlic.
Pour the wine mixture over the vegetables in the pan and mix to combine. Spread the vegetables out into a single layer and top with the chicken thighs and any juices that have collected on the plate.
Roast for an additional 20 to 25 minutes until the chicken thighs are done. If you'd like more browning on the chicken, turn on the broiler and broil for 2-3 minutes more.
You can serve on the sheet pan or transfer to a shallow casserole dish. If there seems to be too much liquid, spoon off a bit of the excess. We like it for serving over noodles and to soak up with bread. Garnish with fresh parsley, fennel fronds or fresh basil if desired.
Very good served over egg noodles with a shave of parmesan cheese or pecorino romano.