It's not a holiday meal without this casserole star, so don't let these green bean casserole mistakes happen to your dish.

It wouldn't be a holiday dinner without green bean casserole. Yet, the perfect green bean casserole, one that tastes creamy, indulgent, and oh-so-good, can be a bit difficult to achieve. A few common mistakes can stand between an impressive side dish and one that is doomed for leftover purgatory. To make sure your side dish is super tasty, avoid these mistakes when whipping up that favored casserole this year.

Best Green Bean Casserole in a white dish
Credit: Cynthia Ross

Mistake #1: Piling on the Cheese

Cheese makes a casserole taste great, but you can use too much of a good thing. "I heart cheese, but I am not a fan of cheese on my green bean casserole," says Dana Angelo White, MS, RD. "A bunch of shredded cheddar distracts from the fresh flavor of the green beans." If you must, add a sprinkle of Parmesan, as it complements the mushrooms, and a little extra umami flavor never hurts.

Mistake #2: Not Using Other Veggies

Why stick with just green beans when you can make a medley of veggies for added flavor? "Green beans are the star here, but adding fresh sliced mushrooms makes for a next-level casserole," White says. You can get in more health benefits, like fiber and vitamins, but you can also improve the flavor by introducing some other tasty flavors that all mix well with one another. And extra veggies bulk up the casserole and create a thicker texture.

Mistake #3: Creating a Soggy Topping

The crispy topping of a green bean casserole is the best part, especially when the interior of the casserole is soft and creamy. It's all about a balanced texture throughout the dish. "French fried onions are classic, but you can also use panko bread crumbs, too, " White says. "Mix with olive oil or some melted butter and sprinkle over top before baking," she suggests. And if you want to stick with the classic fried onions you can, of course, just make sure they're nice and crispy on top. Don't let them sit for too long after baking, as the steam from the casserole will turn them limp.

Mistake #4: Messing Up Those Green Beans

Whatever you do, don't overcook the green beans. "If using fresh green beans, blanch in boiling water with salt only cook for 2 to 3 minutes max, says Chef Palak Patel from the Institute of Culinary Education. "Put cooked beans in an ice bath to preserve the vivid green color."

Make sure you have the right beans to begin with, as well "Frozen green beans are the best green beans to use for green bean casserole," Patel says. "French cut is the best to coat each bean with sauce, too."

Mistake #5: A Runny Casserole

Who wants that? Be sure that frozen green beans are completely defrosted and drained before adding them to the casserole, Chef Patel says. If you don't, the excess water from the beans can leak out into the casserole and make it thin and runny.

If you sense it's a little watery, "add a thickener like roux or starch to absorb the additional liquid or cook a little longer," she says. That'll give it that rich, dense consistency you're looking for.

Mistake #6: Adding Toppings Too Early

Don't start throwing toppings on the casserole before it's cooked through. "Adding topping too early [is a mistake] because the onions get soggy or burn," Chef Patel says. Instead, wait it out. Just a few minutes before the dish is finished and ready to be pulled from the oven, you can then add in those toppings. This will ensure the center is cooked and the toppings don't disappoint.