1 lb. fresh green beans, trimmed
2 tbsp. extra-virgin olive oil
1/2 tsp. kosher salt
2 cloves garlic, finely chopped
1/4 tsp. freshly ground black pepper, plus more
1/2 c. shredded Parmesan
1/4 c. shredded mozzarella
Preheat oven to 425°. On a large sheet pan, toss green beans with oil and salt. Bake, tossing after 7 minutes until beans are crisp-tender, 10 to 15 minutes.
Toss green beans again; sprinkle with garlic and 1/4 teaspoon of pepper. Top with Parmesan and mozzarella.
Heat broiler. Broil beans, watching closely until cheese is melted and golden brown, 2 to 3 minutes. Season with more pepper and serve.