Cut the stalks off the fennel bulb and trim the root end. Reserve some of the fennel fronts for garnish if desired. Cut the bulb in half lengthwise and then each half into 4 wedges.
Cut the stem ends off the pearl onions and then peel off the outer skin. Leave the onions whole.
Heat a large sauté pan and add the olive oil. Add about half of the fennel in a single layer in the pan and cool until golden brown. Turn the fennel over and cook the other side. Season with salt and pepper. When both sides are brown, move the fennel pieces to a 9”x13” baking dish.
Cook the remaining fennel pieces along with the pearl onions until brown and add them to the baking dish.
While the sauté pan is still hot, add the wine and chicken stock, bring to a simmer, then pour over the fennel and onions in the baking dish. Add the rosemary branches to the pan and then place the pan in the oven, uncovered.
Cook for 35-45 minutes or until the fennel is tender.