Heat 1 tablespoon of olive oil in the skillet until shimmering. Add the wingettes to the skillet and cook over moderately high heat until golden on the bottom, about 4 minutes. Add the fennel, scallions, sage and a generous pinch each of salt and pepper and transfer the skillet to the oven. Roast for about 30 minutes, stirring once, until the fennel is tender and the wingettes are cooked through. Let cool slightly, then remove the meat from the wingettes; discard the skin and bones. Add the meat to the vegetables.