Position a rack in the center of the oven and heat the oven to 425ºF.
Heat 2 Tbs. of the oil in a 12-inch heavy-duty skillet over high heat. Add the fennel, sprinkle with salt, and cook, stirring occasionally, until nicely browned in places, about 5 minutes—don’t stir too often or the fennel won’t brown. Remove the skillet from the heat. Transfer the fennel to a 9x13-inch baking pan, spreading it evenly. Layer the scallions on top of the fennel, sprinkle with 1/2 tsp. salt, and scatter the olives over the scallions.
Put the flour in a shallow dish. Trim any excess fat from the chicken and season the chicken with 1 tsp. salt and 1/2 tsp. pepper. Dredge the chicken in the flour.
Heat the remaining 3 Tbs. oil in the skillet over high heat. Turn on the exhaust fan. When the oil is very hot, add the chicken (it may be a tight fit, but the chicken will shrink as it cooks) and sear until the first side is well browned, 3 to 4 minutes. Reduce the heat to medium-high, flip the chicken using tongs, and cook until the second side is well browned, about another 3 minutes.
Arrange the thighs on top of the vegetables. Carefully pour the wine into the skillet and cook over medium-high heat, scraping up bits from the pan with a wooden spoon, until the wine reduces by half, about 1 minute. Add the broth and bring to a simmer. Pour the wine mixture over the chicken and bake until the chicken is cooked through and the fennel is tender, 15 to 20 minutes.
Serve with rice pilaf flavored with lemon zest and chopped fresh parsley.