A make ahead casserole consisting of vegetables and a creamy sauce – served as a side or a main, this casserole will most certainly get vegetables onto your table and into the bellies of your loved ones. This dish can easily be reheated without losing any of the creaminess, cheesiness, or texture!


Oh, Make Ahead Creamy Vegetable Casserole, where do I start? I could have eaten this entire dish! Oh, sweet Lord, it’s absolutely delicious! I love the combination of the cauliflower, the green beans, the carrots, the green peas, and the corn – all tossed with a thick, creamy mushroom sauce. It was so hard to wait until these photos were taken before digging in with the biggest spoon I could find!
It’s meals like this that make cooking more enjoyable. It’s the simple, inexpensive ingredients, coupled with next to no technique, and gorgeous, mouth-watering results. This side will be my new equivalent of a green bean casserole for all future Thanksgivings to come.
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FROZEN VEGGIES MAKE THIS DISH AFFORDABLE AND EASY!
But, get this, Dear Reader; you could use any frozen vegetable you like in this dish. For example, if cauliflower is not your preferred vegetable of choice, you could certainly switch it with frozen broccoli florets instead. And the vegetable medley that I used is adaptable as well. In the frozen food section of my local grocery store, there are many, many varieties to choose from.
I’m thinking about trying this exact same recipe with an Asian-inspired vegetable mix as well. I used to buy an Asian frozen vegetable mix that consisted of red peppers, mushrooms, baby corn, onion, and bamboo shoots. Sounds good, right? The only question is, would I use a cream of mushroom soup, or would I change it up and use a cream of asparagus or cream of broccoli soup instead? The options are quite endless and the result would be a new taste every time!

INGREDIENTS NEEDED TO PREPARE THIS RECIPE
The following is a list of the ingredients needed to prepare this recipe. For exact amounts and measurements, refer to the printable recipe card located near the bottom of this post.
- Cauliflower – Use bagged, frozen cauliflower from your grocer’s freezer section. It’s cheap and you don’t have to spend the time to cut it all up into florets!
- Frozen Mixed Veggies – Any of your favourite mixed veggie blends will do. To keep this one simple, I used a frozen blend consisting of carrots, peas, and corn.
- Cream of Mushroom Soup – Straight from the can, folks! Just like that green bean casserole that everyone loves, the cream of mushroom soup will keep this casserole creamy and moist.
- Sour Cream – Because the creamier, the better, right?
- Cheese – I used white cheddar, but you can use any flavour you like.
- Salt and Ground Black Pepper
- French Fried Onions – Like the green bean casserole topping, this one paired greatly with it too!

HOW TO MAKE THIS CASSEROLE:
You just know that this is going to be a breeze, right? Come on!!! We are using frozen vegetables and a can of soup, for crying out loud! That’s about as basic as it gets when it comes to whipping up a casserole. But, you just can’t beat it! I’d love to pretend that I’m too pretentious to crack open a can of soup for my casserole. In fact, I’d love to say I grew the vegetables myself, but that’s not my life, folks! We’re making this recipe easy and budget-friendly at the same time!
The first thing you want to do when preparing this Make Ahead Creamy Vegetable Casserole is to preheat your oven to 350 degrees F. Next, add all of the ingredients to a large bowl, remembering to set aside half of the French Fried Onions for later. Use a spatula and mix until everything is evenly distributed throughout the bowl.
Next, transfer everything to a casserole dish. There’s no need to grease it first. The cheese, soup, and sour cream will make sure it doesn’t stick! Now, bake this for 50 minutes. Then, remove it from the oven and top it with the remaining French Fried Onions and some chopped parsley to garnish. Serve it immediately, or wait for it to cool completely before freezing.

MAKING THIS DISH AHEAD OF TIME? HERE’S HOW:
If you are preparing this dish ahead of time and would like to freeze it, follow the same steps as if you were preparing it for tonight’s dinner. Once you remove it from the oven, allow the casserole to cool completely. Do not add the remaining fried onions or garnish with parsley. There’s no need for that now.
Once cooled, transfer the casserole to a freezer-friendly container. Place a tight-fitting lid on it and freeze it for up to three weeks. Remember to transfer the frozen casserole from the freezer to the refrigerator for at least 12 hours before planning to reheat. When ready, gently stir the casserole and transfer it to a proper baking dish. Bake at 350 for 15-20 minutes or until bubbly and hot. Remove from the oven and garnish with those French Fried Onions and chopped parsley we talked about earlier. Enjoy!
CHEESE CHOICES – IT’S A HARD LIFE!
Even the type of cheese is adaptable. Cheddar is obviously my favourite type of cheese, and I’m sure you can find evidence of that in almost any recipe on my blog that has cheese as an ingredient, but you could use Gouda or Havarti or even Swiss! Since you want to flavour of the vegetables and the creamed soup to be the highlight of the dish, I would not recommend a strong cheese, but you decide!

FREEZER FRIENDLY TOO!
As you can see from one or two of my photographs, this is the perfect make ahead dish. Once the casserole had completely cooled, I transferred some of it to a container for refrigeration. Are those aluminum storage containers not the cutest? I found them while shopping at HomeSense. I had to have them and thought immediately about featuring one of them in a blog post that would allow for freezer-friendly recipes.
When the time came to serve this dish up, I convinced John.e and McKenna to add extra crispy French fried onions to their plates. I always watch what I eat very carefully throughout the week, so while they both dined on this deliciousness, I ate a humble salad with canned tuna. I was living vicariously through both of them. Ha!
The recipe below is one I’m sure you will keep coming back to over and over again. Not only is Make Ahead Creamy Vegetable Casserole a great alternative to the usual dishes served at your family’s holiday functions, but it’s a great side or main as well. Think about this casserole for your next Meatless Monday dinner!
QUESTIONS?
If I have not answered all of your questions in the text above, don’t hesitate to reach out to me! You can contact me by sending me a message in the comments section further down the page. I will try my best to answer as soon as possible! You might reach me even faster by following me on Facebook and sending me a private message. Scroll down below the recipe card to find my Follow Me on Social Media box and never miss another recipe!
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Make Ahead Creamy Vegetable Casserole
Ingredients
- 4 cups cauliflower florets, frozen
- 4 cups mixed vegetables, frozen (carrots, corn, peas, etc.)
- 20 ounces canned cream of mushroom soup
- 1 cup light sour cream
- 2 cups white cheddar cheese, shredded
- 1/2 teaspoon ground black pepper
- 1/2 teaspoon salt
- 1 cup french fried onions
- parsley for garnish, optional
Instructions
- Preheat oven to 350 degrees.
- In a large bowl, stir all ingredients together, saving half cup of the french fried onions for later. Once fully mixed together, transfer to a large casserole dish.
- Bake for 50 minutes.
- Remove from oven and top with fresh chopped parsley and the remaining french fried onions.
- Serve immediately or allow to cool completely before packaging for freezing. See notes.
Notes

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Sarah @ Champagne Tastes says
Oooo I bet those fried onions on this make it AMMAAAAZING! I never thought about adding them to anything other than mushroom soup or green bean casserole!
Patsy says
I just made this this! I didn’t have the fried onion bits, So I covered it with buttered bread crumbs! I also made Meat loaf and mashed Potatoes! The creamy vegetable dish was an after thought,
Big change from Just corn or green beans! It was delicious, Boy friend loved it! Thanks for the recipe!
byronethomas@gmail.com says
That sounds like a great alternative, Patsy!
Ashley says
Move over green bean casserole! I think this sexy dish might take over this Thanksgiving! Looks amazing 🙂
Emily P says
I am obsessed with this dish!! Thankfully, my husband isn’t. Which means more for me!
byronethomas@gmail.com says
Hahaha! Emily, you think much the same way I do! More for me. 🙂
Sarah says
I am wondering if this could be made in the crockpot to save space in the oven on Thanksgiving? If so, what do you think the time would be? Thanks!
byronethomas@gmail.com says
Hi Sarah,
I have never used a crock pot, so I’m unsure of how they cook in terms of temperatures and cooking time. I’m sorry I couldn’t be of more help.
Gina Curry says
I use frozen broccoli cauliflower and carrot mix, 2#. I use 1 can cream of chicken soup. No need to precook veggies, just defrost. And use shredded Swiss cheese. One of our favorite side dishes!
Lucy says
Do you cover the casserole?
byronethomas@gmail.com says
No, I did not.
Haley says
What size pan do you use?
byronethomas@gmail.com says
I’m using an oval pan, but essentially, it’s a 9 x 13 inch pan.
Judy says
Are the vegetables thawed?
byronethomas@gmail.com says
No, just put right in there from the freezer.
Kacie says
Do you think you would cook this on the grill?
byronethomas@gmail.com says
Hi Kacie, I’ve never tried it on the grill, but I would think that if you cooked it in a heavy-duty foil pan, it should work quite well!
Kim says
Just wondering if I can use fresh vegetables and increase the cook time?
Thanks!!
Janet Fischer says
I roasted a whole pan full of veggies from my garden..it was excellent this way! Thanks for the recipe will definitely be making again!
Lois Hunter says
I made this cause I like veggies,and it’s good to have a meatless night.i made this without my Sister knowing
i put light sour cream in it,and She ate it and LOVED it.
and she said yes I will eat this casserole again.
another win for Vegetables
byronethomas@gmail.com says
Awesome, Lois!
Serika yates says
Can I make this in the morning and leave it the fridge all day and cook it when I get home later?
byronethomas@gmail.com says
Yes, I’m sure it would be great!
B heldman says
Cannot use creamed soups. Can u suggest an alternative please
Kathy Childs says
Well, I was looking for a recipe to cook all the leftover vegetables from my vegetable platter (which I served with appetizers). Clearly, folks don’t eat healthy food at cocktail parties. SOOO, I boiled them until just under fork tender (carrots, celery, green bell peppers). Once cooked I then cut them into small bite-size pieces and added corn and peas. Then I followed your recipe! It turned out the way I wanted. Thank you for sharing your recipe for those of us who feel fine using canned soup, 🙂
Jody says
Thank you for bringing this to us, I’m on minimum wage and some weeks after bills and gas i have $30 in my pocket for the week. (I’m single so that’s manageable). Having the cheese and sour cream already. I bought the frozen veg, fried onions, and added 2 cans of chicken. Came in at $18 doller’s. Eat that 3 times a day till its gone. This is a recipe I’ll use again.
Ellen says
Made this with a small bag of cauliflower and a 52 ounce bag of Asian vegetables. I threw in a good helping of minced onions and about a tblsp of minced garlic. I mixed all this together and let it marry overnight in the fridge. After baking, I topped it with a stack of Ritz crackers crushed in a stick of melted butter, and then topped with a can of fried onions. Returned to oven for an additional 15 minutes. Delicious!
Sadie says
I made this for my family of picky eaters and they loved it. I was so happy to hear them ask me to make a vegetable dish again. That never happens. It was quick and easy with very little mess. I was surprised at how good and convenient using frozen veggies was. It’s definitely on our rotation now.
byronethomas@gmail.com says
That’s such a win-win, Sadie! 🙂
Linda Ruble says
I just made a half recipe of this to try it out for a luncheon for a bowling group for next week. I only used the frozen mixed vegetables with corn, green beans, peas and carrots. It tasted wonderful with a rotisserie chicken!!! I wished I had made biscuits to go with it because it reminded me of the inside of a chicken pot pie!!