Preheat oven to 400℉. Place the fresh green beans on a large baking sheet. Drizzle with the olive oil and season with the salt. Toss to coat, then spread green beans out in one even layer.
Bake until crisp-tender, about 13 to 15 minutes, tossing the green beans halfway through the cooking time.
Carefully remove from oven and sprinkle the fresh minced garlic and black pepper all over the green beans. Sprinkle the Parmesan and Mozzarella cheese evenly over the top.
Turn the broiler on high, and place green beans back in the oven. Broil until the cheese is melted and golden (*this takes about 2 minutes. Stay and watch the entire time so it doesn't burn!) Serve warm and enjoy!