Heat a large cast-iron skillet or shallow Dutch oven over medium high heat.
Liberally season the chicken with salt and pepper. Add 2 to 3 tablespoons of the reserved sun-dried tomato oil to the hot skillet and, working in batches if necessary, place the chicken skin-side down in a single layer. Cook until golden brown and crispy, 5 to 7 minutes. Flip and cook the other side for 2 minutes. Remove to a plate and set aside (the chicken will not be fully cooked), leaving the fat in the skillet.
Reduce the heat to medium. Add the sliced fennel and sun-dried tomatoes and cook, stirring occasionally, until the fennel starts to soften slightly, 2 to 3 minutes. Season with salt and pepper. Add the 2 to 3 tablespoons chopped fennel fronds, the rosemary and thyme. Cook, stirring occasionally, for 1 minute. Add the sherry and stir, scraping up any browned bits from the bottom of the skillet with a wooden spoon.
Add the beans and stock, stir and then season with a little more salt and pepper. Return the chicken to the skillet, skin-side up, nestling it into the liquid.
Roast in the oven until the chicken is cooked through, 35 to 45 minutes. If the chicken skin isn't as crispy as you'd like, pop the skillet under the broiler for a few minutes.
Remove from the oven and let the rest for 10 minutes before serving to allow the juices to reabsorb and the sauce to thicken slightly. Garnish with fennel fronds and serve family style.