Preheat oven to 350 degrees F. In a large pan, cook sausage until browned and crumbled. Remove from pan, set aside, and drain grease.
In the same pan, melt the stick of butter and add the apples, celery, leeks, and poultry seasoning. Saute until softened, approximately 8-10 minutes.
Add the rosemary, cranberries, and cooked sausage, mix all ingredients together well.
Stir in the dried bread crumbs until combined. Season to taste with salt and pepper. Moisten with chicken stock. Bake in a buttered casserole dish, covered for 45 minutes. Uncover and bake for another 15 minutes.