Preheat your oven to 350°F (175°C) and prepare a greased 2-quart baking dish.

In a large skillet, melt butter over medium heat, add diced onion and sliced mushrooms, sauté for 5-7 minutes until tender, then add minced garlic and cook for another 1-2 minutes.

In a separate pot, bring low-sodium chicken broth to a boil, add green beans and cook for about 8 minutes until crisp-tender, then drain.

In a large mixing bowl, combine the sautéed mixture with the cooked green beans, stir in the cream of mushroom soup, grated Parmesan cheese, salt, and pepper until mixed.

Pour the mixture into the greased baking dish, spreading it evenly.

Top with crispy fried onion strings to add crunch.

Bake in the preheated oven for 20 minutes until hot and bubbly with a golden top.

Remove from oven and let cool for a few minutes before serving.