Place beans in a steamer basket; place in a saucepan over 1 in. of water. Bring to a boil; cover and steam for 7-8 minutes or until crisp-tender. Transfer to a 2-qt. baking dish coated with cooking spray.
Combine the oil, vinegar, salt and pepper; drizzle over beans and toss to coat. Set aside.
In a small skillet, saute onion in butter until tender. Add garlic; cook 1 minute longer. Remove from the heat; stir in bread crumbs and cheese. Sprinkle over beans. Sprinkle with paprika if desired.
Bake, uncovered, at 350° for 18-22 minutes or until topping is lightly browned.