Add the frozen green beans and chicken broth to a large skillet. Cover and bring to a simmer over medium heat.

Simmer, covered, for 8 to 10 minutes, until the beans have absorbed the broth, turned bright green, and a fork pierces them easily. Start checking at 8 minutes so you can stop them while they are tender, before they turn mushy. Transfer the beans to a serving dish.

Add the butter, Italian seasoning, salt, and pepper over the beans and toss until it melts and coats the beans. Taste before salting, since the broth, butter, and Parmesan all add salt.

Sprinkle the Parmesan and red pepper flakes, if using, over the top. Adding the cheese in the serving dish instead of the skillet keeps it from sticking to the pan.