Heat the butter in a large skillet over medium heat and saute the apples for 4 to 5 minutes, turning frequently, until golden on both sides. Remove from the heat and set aside. Heat the oil in a clean skillet and saute the garlic, parsnips, onions, and fennel seeds for 10 minutes, or until lightly browned. Add the sage, cider or apple juice, and stock; bring to a boil, cover, and simmer gently for 12 minutes. Add the apples and their juices to the pan and simmer for 3 minutes more. Strain the juices into a small saucepan and keep the parsnip mixture warm in a serving dish. Stir the mustard and honey into the pan, bring to a boil, and simmer rapidly or 5 minutes, or until the liquid is reduced slightly and glossy. Pour over the vegetables, season to taste with salt and pepper, and serve at once.