Mozzarella Zucchini Skillet

2 T. oil
5 medium zucchini, sliced
1 medium onion, chopped (about ½ cup)
¼ tsp. garlic powder or 2 cloves, minced
1 ½ C. spaghetti sauce
½ C. shredded mozzarella cheese

Heat oil in 12-inch skillet over med-high heat. Add zucchini, onion, and garlic and cook until the vegetables are tender-crisp. Stir in the sauce and heat through. Sprinkle with cheese. Cover and cook until the cheese melts.