This is a great stuffing for turkey but would also go well with pork.
In a large skillet over high heat, melt butter until just golden brown. Add the onions and sauté on high, stirring frequently, until browned, about 5 minutes. Reduce heat to medium and sauté for a further 5 minutes until onions are very soft. Add the sliced garlic and sauté 2 more minutes. Add Calvados and 1 cup chicken stock. Cook covered, on medium heat, about 10 minutes. Add the apples and herbs and cook for a further 5 to 8 minutes or until apples are tender. Cool to room temperature.
Preheat oven to 325 degrees F. Butter a casserole dish.
Combine the bread, chestnuts, prunes and apple mixture in a large bowl. Season with salt and plenty of freshly ground pepper. If mixture has absorbed all the liquid, add the remaining 1/2 cup of stock.
Transfer to a buttered casserole dish. Bake covered, until lightly golden on top and hot throughout, 30 to 40 minutes.