Slow Cooker Holiday Green Bean Casserole

Name: Slow Cooker Holiday Green Bean Casserole
Ingredients: 2 pounds fresh green beans trimmed (or 2 16 oz bags frozen green beans, thawed); 1 15 ounce jar Alfredo sauce; 1 8 ounce can diced water chestnuts, drained; 1 6 ounce can sliced mushrooms, drained; 1 2 ounce jar diced pimentos, drained (I substituted 1/4 cup chopped Mezzetta roasted red bell pepper strips); 1 cup grated Parmesan cheese; 1/2 teaspoon freshly ground black pepper; 1 6 ounce container French-fried Onions, divided; 1/2 cup coarsely chopped pecans