Step 1

Preheat the oven to 350 degrees. In a large skillet, melt butter over medium heat.

Step 2

Saute onions and mushrooms until just tender, stirring occasionally. Add garlic and cook for another 1-2 minutes, then remove from heat and set aside.

Step 3

In a medium saucepan, combine green beans with chicken broth. Bring to a boil.

Step 4

Continue cooking for about 8 minutes until beans are crisp-tender and drain.

Step 5

Prepare a 2-quart baking dish by spraying it with cooking spray. In a large bowl, combine the soup, mushroom mixture, green beans, Parmesan, salt, and pepper.

Step 6

Transfer the mixture to the prepared baking dish and top with crispy onion strings.

Step 7

Bake at 350 degrees for 20 minutes, or until the casserole is heated through.