In a medium non-stick saucepan, sauté onion in olive oil until soft (about three minutes). Add garlic and sauté one minute more.
Add broth, grated carrots, salt, and pepper. Bring to a boil. (Add dried basil at this time if you aren't using fresh.)
Stir in the orzo. Cover, reduce heat and simmer about 15 minutes, stirring occasionally, until the orzo is tender.
Remove from heat; stir in zucchini, cheese, and fresh basil if you are using it. Cover and let stand about 3 minutes to allow the hot orzo mixture to melt the cheese and cook the grated zucchini.
Serve warm.
Notes
BROTH: If I use a commercially prepared vegetable broth, I omit the salt. If I use homemade broth, I dilute it dramatically so that the broth flavor doesn't overpower the other vegetables.