1. Set the oven rack in the center of the oven and preheat to 325°F.
2. To a large bowl, add the chicken. Pat generously with salt, pepper, and paprika. Toss with the flour.
3. In a large heavy, oven proof frying pan (ideally cast-iron, 12 inches or bigger), over medium-high heat, add the oil. Set the thighs skin side down in the pan and sear for about 8 minutes, or until the skin turns golden brown. Flip the thighs.
4. Add the onion and fennel, cut sides up, and nestle the carrots, parsnips, and garlic in the pan. Everything will shrink as the contents braise. Add the stock and wine, and if necessary extra stock, or water, to bring the liquids roughly three-quarters of the way up the chicken. Top with the herbs and lemon slices, and drizzle with olive oil. Bring to a simmer, then turn off the heat. Cover the pan tightly with a lid or aluminum foil.
5. Bake for 30 minutes. Remove the foil and bake for another hour, or until the tops of the veggies are browned and the liquid has reduced by about two-thirds. During the last 30 minutes make sure the liquids don’t reduce and blacken at the bottom of the pan. If they do, add stock or water ½ cup at a time. In the last 15minutes, nestle the greens between the pan contents so they simmer.