Place beef brisket in a large pot and cover with boiling water. Add onion, garlic, and cloves; bring to a full boil and lower heat. Simmer slowly, partially covered, for about 3 hours, until very tender when tested with a fork. Meanwhile, mix glaze ingredients together and set aside. When meat is done, remove from pot and drain. Place meat in an ovenproof serving dish and pour glaze mixture over top to coat thoroughly. Bake at 350 degrees F for 30 minutes, or until glaze is nicely browned.
Prepare Apple Garnish: Peel and core the apples. Slice crosswise into ¼-inch rings. Melt 2 tablespoons of the butter in a large skillet and add a single layer of apple slices; saute until browned, about 5 minutes. With a slotted spoon, transfer apples to a bowl. Repeat until all apples are cooked, adding butter as needed. Add brown sugar to the butter remaining in the skillet and stir until it dissolves. Add the Calvados and nutmeg, and bring to a boil. Boil for 5 minutes, stirring constantly. Return apples to the skillet, reduce heat, and simmer another 5 minutes, until apples are heated through. Keep warm. Remove meat from oven to a heated platter. Garnish with apple rings and sauce. Delicious served with tender parsnips.