Heat olive oil in a large nonstick skillet over medium heat.

Add chopped onions, sliced carrots, sliced parsnip, and minced garlic to the skillet.

Cover the skillet and cook for 5 minutes, or until the vegetables are tender.

Transfer the sautéed vegetable mixture to a 5-quart slow cooker.

Add cooked great northern beans, vegetable broth, dried thyme, salt, black pepper, diced tomatoes (undrained), and bay leaf to the slow cooker.

Cover the slow cooker and cook on LOW for 8 hours, or until the vegetables are very tender.

Discard the bay leaf.

In a small bowl, combine breadcrumbs, grated parmesan cheese, and melted butter.

Toss the breadcrumb mixture with a fork until the crumbs are evenly moistened.

Stir the breadcrumb mixture and chopped vegetarian sausage into the bean mixture in the slow cooker.

Sprinkle chopped fresh parsley over the top before serving.