In a saute pan or frying pan saute the onion and garlic till soft, about 5 min on medium heat.
Add the zuchini and continue sauteing until lightly browned.
Add the can of tomato sauce and toss lightly until hot.
Sprinkle the shredded parmesan cheese over the top and when it melts its ready. The zuchini should not be swimming in tomato sauce, it should just be coating the squash so you might have to add more squash or less tomato sauce to make it the right consistancy.