1. Combine 1 1/2 teaspoons salt, 1/2 teaspoon pepper, and next 5 ingredients (through cloves) in a small bowl. Rub mixture over all sides of brisket. Place brisket in a 5- to 6-quart slow cooker. Add stock and next 5 ingredients (through bay leaves). Arrange cabbage halves over top. Cook on LOW 8 hours or until beef is very tender. Transfer beef to a cutting board; discard bay leaves.
2. Place potatoes and carrots in a large saucepan; add cold water to cover potatoes by 1 inch. Bring to a boil; cook 8 to 10 minutes or until tender. Drain. Toss with remaining 1/4 teaspoon salt, remaining 1/4 teaspoon pepper, and butter. Cut brisket across the grain into thin slices. Cut each cabbage half into 4 wedges. Serve brisket with onions, cabbage, potatoes, carrots, and jus.