1.Heat oil in a large saucepan over medium-high heat. Add onion and cook 3 minutes, until soft. Add broccoli and broth and bring to a boil; reduce heat to medium and simmer 3 minutes, until broccoli is tender.
2.Reduce heat to low, add cheese and stir until cheese melts; stir in milk and garlic powder.
3.Whisk together water and cornstarch. Add mixture to pan and simmer 2 minutes, until thick. Serve hot.
Yields about 1 1/2 cups per serving.