1. Combine broth, potato, and onion in a sauce pan; bring to a boil.
2. Reduce heat, cover and cook 10 minutes or until vegetables are tender.
3. Mash potato cubes against side of pan using fork.
4. Stir together cornstarch and a little of the milk.
5. Add broccoli and carrot.
6. Stir and cook until thickened and bubbly.
7. Cook and stir 2 minutes more.
8. Stir until cheese is melted.