Vegetarian White Bean and Thyme Cassoulet

This is a great vegetarian casserole.  Hearty, stick to your ribs without the meat.  Add a good French baguette, soft butter and you've got a winner.

1 tablespoon olive oil
1 1/2 cups chopped onion
1 1/2 cups (1/2-inch-thick) slices diagonally cut carrot
1 cup (1/2-inch-thick) slices diagonally cut parsnip
2 garlic cloves, minced
3 cups cooked Great Northern beans
3/4 cup vegetable broth
1/2 teaspoon dried thyme
1/4 teaspoon salt
1/4 teaspoon freshly ground black pepper
1 (28-ounce) can diced tomatoes, undrained
1 bay leaf
1/4 cup dry breadcrumbs
1 ounce grated fresh Parmesan cheese (about 1/4 cup)
2 tablespoons butter, melted
2 links frozen meatless Italian sausage, thawed and chopped
2 tablespoons chopped fresh parsley

Heat oil in a large nonstick skillet over medium heat. Add onion, carrot, parsnip, and garlic; cover and cook 5 minutes or until tender.
Place in a 5-quart electric slow cooker. Add beans and next 6 ingredients (through bay leaf). Cover and cook on low 8 hours or until vegetables are tender.
Combine breadcrumbs, cheese, and butter in a small bowl; toss with a fork until moist. Stir breadcrumb mixture and sausage into bean mixture; sprinkle with parsley.