Sausage, Apple and Cherry Stuffed Pork Loin

1 (4-5 lb.) pork butt roast 1 tbsp. salted butter 1 tbsp. olive oil 12 ounces ground sausage 3 large apples, chopped 1 shallot, chopped 1 tbsp. garlic, minced 1/2 cup walnuts, chopped 1/2 cup dried cherries 1/2 cup apple sauce Salt and pepper Kitchen twine Large bunch of parsley chopped 2 teaspoons thyme 6 [...]