Preheat oven to 350 degrees. Butter a medium size casserole dish. Place a single layer of potatoes in dish and top with potatoes, parsnips, carrots and onions. Season with salt and pepper, dot with 2 tablespoons butter and sprinkle with 1/4 cup of cheese. Place a second layer of vegetables and repeat process. Pour stock over vegetables and cover with aluminum foil. Bake for 40 minutes or until vegetables are tender. Remove foil and top with remaining Parmesan and bake until golden. Serve hot.