Mixed Vegetable Casserole

This mixed vegetable casserole has a little bit of everything—tender veggies, a creamy and cheesy filling, and a buttery cracker topping that bakes up golden and crunchy. It’s cozy, flavorful, and simple to make, making it the perfect side dish for holidays, family dinners, or potlucks. 

Why I Love This Mixed Vegetable Casserole

Cold weather calls for comfort food, and this vegetable casserole has been one of my go-to recipes every fall and winter. It’s hearty, creamy, and incredibly satisfying, yet still light enough to serve as a veggie-forward side. I first brought it to Thanksgiving one year, and since then, it’s become one of my family’s favorite Thanksgiving casseroles. Every time I make it, it’s one of the first dishes that everyone grabs for!

What I love most about this recipe is how quick and convenient it is. It uses frozen vegetables, so there’s no need for chopping or prep work—just cook them briefly, mix them with the creamy filling, and let the oven do the rest. It’s a lifesaver when you need an easy side dish that still feels homemade and special.

This casserole also makes a great option for feeding a crowd. The recipe yields the perfect amount for family dinners or potlucks, and both kids and adults always love it. It’s also a sneaky way to get everyone to eat more veggies!

Another reason I love this recipe is how versatile it is. You can use almost any mixed vegetable blend—broccoli, cauliflower, carrots, green beans, peas, or corn. Try experimenting with different combinations to find your favorite version. No matter what you use, you really can’t go wrong with this comforting, crowd-pleasing veggie casserole.

Ingredients You'll Need

• 20 oz. Mixed vegetables- frozen works best. I used a bag of green beans, peas, carrots, and corn.
• ½ Cup Onion- diced into small pieces. A white onion works well here.
• 1 Tbsp. Butter- I used unsalted to sauté the onions.
• 1 Cup Condensed cream soup- I used cream of mushroom soup. You can also use cream of celery soup or cream of chicken soup instead.
• ⅓ Cup Mayonnaise- to add more creaminess to the sauce.
• ½ Tsp. Garlic powder- for a little savory flavor.
• Salt- just a pinch.
• 1 Cup Cheddar cheese- I used sharp cheddar cheese to add more flavor to the crackers.
• 2 Cups Butter crackers- crushed for the topping. Ritz crackers or Club crackers work well.
• 3 Tbsps. Melted butter- for mixing the crackers.

How To Make Mixed Vegetable Casserole

Step 1: Prep and Cook the Vegetables

Preheat the oven to 350°F and grease a baking dish with nonstick cooking spray. Bring a large pot of salted water to a boil, and add the frozen vegetables to it. Cook them for 1-2 minutes, then drain well and place the vegetables in a large bowl.

Step 2: Sauté the Onions

While the veggies are boiling, sautée the sliced onions in a large frying pan with a tablespoon of butter. Cook for about 3-5 minutes, stirring frequently, until the onions are soft.

Step 3: Combine the Ingredients

Add the sautéed onions, cream of chicken soup, water, mayonnaise, garlic powder, and salt to a mixing bowl and stir. Then add the mixture to the bowl of veggies and mix until everything is fully incorporated.

Step 4: Assemble the Casserole

Transfer the filling to the prepared baking dish. Make sure the casserole is in an even layer. Then top it with the shredded cheddar cheese, followed by the crushed crackers. Finish it off by pouring the melted butter evenly on top.

Step 5: Bake and Serve

Put the casserole in the oven and bake it, uncovered, for 15-20 minutes or until the filling bubbles and the crackers are browned. Let it cool, then serve warm with anything you want and enjoy!

Expert Tips To Make the Best Mixed Vegetable Casserole

• Drain the cooked vegetables completely: Whether you’re using frozen or steamed mixed vegetables, make sure to drain them thoroughly before adding them to the cream soup mixture. Excess water will thin out the sauce, causing your casserole to turn soupy instead of creamy. If you’re using frozen veggies, let them thaw first, then pat them dry with paper towels to remove any extra moisture. This simple step ensures your casserole has a rich, thick filling instead of a watery one.
• Don’t overcook the vegetables: You only need to par-cook or briefly steam the vegetables before mixing them into the casserole—just enough to take the chill off and slightly soften them. Overcooking the veggies early on can make them mushy by the time the casserole finishes baking. You want them tender but still vibrant so they hold their texture after baking.
• Keep some texture in your cracker topping: When crushing the buttery crackers for the topping, leave a few larger pieces mixed in with the crumbs. Those bigger chunks give you that irresistible crispy, crunchy texture that contrasts with the creamy filling underneath. If the topping is crushed too finely, it can turn dense and lose that signature buttery crunch.
• Mix butter evenly into the topping: Melted butter is what helps the cracker topping turn golden and crisp in the oven. Make sure to stir the butter thoroughly into the crushed crackers so every piece gets coated. Unevenly mixed topping can leave some areas dry or under-toasted, while others become greasy.
• Add a layer of parmesan or extra cheese: If you love a deeper cheesy flavor, sprinkle grated Parmesan or shredded cheddar over the top of the casserole before baking. The Parmesan adds a salty, savory finish that enhances the creamy sauce, while the cheddar melts throughout the crust for a gooey finish.
• Let the casserole rest before serving: As tempting as it is to dig in right away, let the casserole cool for about 5–10 minutes after removing it from the oven. This rest time allows the sauce to thicken and set, making it easier to serve clean slices without the filling spilling out. It also gives the flavors a few minutes to meld together for that perfect creamy consistency.
• Make it ahead for busy holidays: This mixed vegetable casserole can easily be prepared ahead of time. Assemble it up to a day in advance, cover tightly with foil or plastic wrap, and refrigerate. When you’re ready to bake, take it out 20 minutes early to come to room temperature and bake as directed. This tip is a lifesaver for Thanksgiving, Christmas, or any large family gathering.
• Customize your mix of veggies: The beauty of this dish is how flexible it is. Try using a blend of broccoli, cauliflower, carrots, green beans, corn, or peas—whatever you love or have on hand. Mixing up the vegetables keeps the casserole interesting every time you make it.

How To Store Vegetable Casserole

• In the fridge: You can either cover your casserole dish with a lid or transfer the leftovers to an airtight container and store them in the fridge for about 3 days.  
• In the freezer: To keep for longer, let the casserole cool completely and then transfer it to a freezer-safe container and freeze for up to 3 months.
• Reheating: I've found the best way to reheat this casserole is in a 350°F oven for 15 minutes. This allows the crackers to crisp back up. You can also pop it into the microwave in 30-second increments for a quicker method, but the crackers will be soggy.

Mixed Vegetable Casserole FAQs

Do I have to use frozen mixed vegetables?

No! You can make this mixed vegetable casserole with fresh, canned, or frozen vegetables—whatever you have on hand. Frozen veggies are the most convenient since they’re pre-chopped and partially cooked, but fresh vegetables work just as well. Just blanch fresh vegetables for 2–3 minutes before mixing them into the filling so they soften slightly. If you’re using canned vegetables, make sure to drain them thoroughly to avoid adding excess liquid to the casserole.

Can I use fresh vegetables in this casserole?

Yes, fresh vegetables make a great option! Try using a mix of broccoli, cauliflower, green beans, corn, peas, or carrots. Cut them into bite-sized pieces and blanch them briefly before combining with the creamy filling. This helps keep their color bright and texture tender without becoming mushy after baking.

Can I make this vegetable casserole ahead of time?

Absolutely! This recipe is perfect for holiday meal prep or busy weeknights. To make ahead, prepare the vegetable filling and add it to your baking dish. Cover tightly with plastic wrap or a lid and refrigerate for up to 2 days. When you’re ready to bake, top with the cheese, crackers, and butter mixture, then bake as directed—adding about 10–15 minutes of extra bake time since it’s starting cold from the fridge.

How do I keep the cracker topping crispy?

To keep your buttery cracker topping crisp and golden, make sure your vegetables are well-drained before assembling. Excess moisture causes sogginess. You can also bake the casserole uncovered for the last 5–10 minutes to help the topping toast evenly. If reheating leftovers, bake uncovered at 350°F until hot and the topping is crisp again.

What can I serve with mixed vegetable casserole?

This vegetable side dish pairs best with comfort food favorites. Try serving it with my cheesy mashed potatoes, cornbread pudding, Pioneer woman stuffing, or meatloaf with stuffing for a hearty meal. It also complements roasted chicken, turkey, or ham—making it a versatile side for both weeknight dinners and holiday spreads.

Can I make this casserole vegetarian?

Yes! This recipe is actually naturally vegetarian since it uses cream of mushroom soup. So make sure you use a vegetable-based cream soup (like cream of mushroom or cream of celery) and skip any meat-based broths.

More Casserole Recipes To Try Next

• Artichoke casserole
• Chicken broccoli stuffing casserole
• Macaroni corn casserole
• Hominy casserole
• Spinach artichoke chicken casserole
• Corn casserole with cream cheese