1. Preheat oven to 350 degrees F. Lightly coat an ovenproof dish with cooking spray.
2. Combine polenta, water, and garlic in the prepared dish. Bake uncovered until the polenta pulls away from the side of the baking dish (40-50 minutes).
3. While the polenta is cooking, coat a nonstick frying pan with cooking spray and heat over medium. Add the mushrooms and onions and saute until liquid has cooked down (4-5 minutes).
4. Add the broccoli and zucchini and saute until veggies reach desired texture (3-4 minutes).
5. When the polenta is done, top with the cooked vegetables. Sprinkle with Parmesan cheese and herbs to taste. Serve immediately.