Easy Broccoli Cauliflower Casserole is cheesy baked vegetable casserole loaded with fresh or frozen veggies in a creamy sauce with a crunchy topping. This veggie casserole recipe is quick to throw together, plus make ahead and freezer friendly!

Cheesy Cauliflower Broccoli Casserole is easy enough to throw together for a weeknight dinner side dish, but also a family favorite at holiday gatherings. This veggie casserole is a great accompaniment to serve with ham, roast turkey, or baked chicken.

It takes minutes to throw together, but if you are prepping for a Thanksgiving, Christmas, or Easter meal, veggie casserole can be refrigerated for a day before baking or frozen.

Broccoli and Cauliflower Casserole Ingredients

Fresh broccoli florets – Substitute frozen California medley or use pre-chopped broccoli florets as a time saver
Fresh cauliflower florets – Substitute frozen California medley or use pre-chopped cauliflower florets as a time saver
Mayonnaise – regular or light
Sour cream – regular or light
Heavy Cream – Milk, half and half, or non-dairy milk may be substituted
Shredded sharp cheddar cheese – Any cheese may be used, but freshly grated is always best
Salt and pepper
Garlic powder
Rice or Corn Chex cereal (for gluten free), or Corn Flakes cereal – For low carb / keto option omit the cereal

How to Make Easy Broccoli Cauliflower Casserole Recipe

Begin by greasing a two quart casserole dish and set aside.
Next, if you did not purchase chopped broccoli and cauliflower, you will want to chop the medium cauliflower head and fresh broccoli into florets.
After that is finished, fill a large, shallow saucepan with one inch of water. Place vegetables in pan and bring water to a boil. Once the water is boiling, cover and reduce heat to simmer. Simmer for 6-7 minutes, stirring halfway through, or until vegetables are crisp tender. Drain and set aside.
In a large bowl, mix together mayonnaise, sour cream, heavy cream, 1/2 cup shredded cheddar cheese (save remaining for later), salt, pepper, garlic powder and 1/4 cup of the crushed cereal. Add the par boiled veggies and stir gently to combine.
Lastly, pour the vegetable casserole mixture into your prepared baking dish. Top with the remaining cereal and cheese.
Bake for 35-40 minutes in 350 degree oven, or until veggie casserole is hot throughout.

Make Ahead Broccoli Cauliflower Casserole

For a make ahead or freezer friendly casserole make the recipe in its entirety up to the point of baking. Make sure the vegetables have completely cooled before covering. Refrigerate up to 24 hours or freeze up to 3 months, securely wrapped.

Thaw overnight in the refrigerator and set out cauliflower casserole to come to room temperature before baking. Add additional 15-20 minutes baking time, or until dish hot and bubbly throughout.

Can I Use Frozen Veggies?

If you don’t have any fresh veggies on hand, but have some frozen veggies you would like to use – that is absolutely fine. Because frozen vegetables can often be purchased as florets, this can also be a time saver for anyone wanting to make the recipe, but not wanting to spend the time (or make the mess) that comes with chopping.

If you go this route, substitute the fresh broccoli and cauliflower florets with three 12 ounce bags of California medley. Alternatively, use a mix of frozen broccoli and cauliflower. Either thaw the veggies first, cook partially in a microwaveable safe dish, or use package steamer bag.

Plan to bake the cheesy cauliflower casserole for an additional 10-15 minutes.

Can I Use Different Vegetables?

Yes, you absolutely can use different veggies. Consider giving some of these a try on loaded cauliflower broccoli casserole:

Frozen peas and carrots
Frozen pepper & onion blend
Add sautéed celery and onions to any vegetable combination for a little extra flavor
Frozen mixed vegetables
Fresh kale, mushroom, spinach and onion. Instead of boiling, sautée the vegetables in your favorite cooking oil
Fresh asparagus
Brussels sprouts

Substitutions for Different Toppings on Veggie Casserole

Breadcrumbs – regular, Italian, gluten-free or panko
Your favorite gluten-free or regular cracker combined with melted butter. Crush two sleeves of cracker and mix together with one stick of melted butter.
Substitute your favorite cheese, such as Swiss or Colby, in place of sharp cheddar. Sprinkle parmesan cheese on top for extra flavor.
French fried onions – add these in the last five minutes to avoid burning
Crushed potato chips

Is Cheesy Broccoli Cauliflower Casserole Low Carb / Keto?

This ooey-gooey baked casserole loaded with vegetables can easily be made into a low carb or keto version for you to enjoy. All you need to do is omit the cereal.

You can also add extra cheese, or use low carb breadcrumbs in place of the cereal topping. For golden brown breadcrumbs, consider adding 1/3 cup of butter to the breadcrumbs.

For another easy, low carb side dish, check out Baked Tomatoes with Cheese!

Alternative low carb / keto vegetable casserole toppings:

crumbled pork rinds
crushed keto crackers
additional cheese
chopped nuts
almond meal

Is this casserole recipe gluten free?

If you are gluten free, then I have some good news for you – this cheesy broccoli casserole recipe is one you definitely can enjoy. Using rice or corn Chex cereal topping keeps the cauliflower and broccoli casserole gluten free.

You do want to be sure to carefully check the cereal topping ingredients. Look for cereals that say “gluten free”. This is especially true of corn flakes because many brands of corn flakes contain malt, which is not gluten free.

Alternative, make your own gluten free breadcrumbs in minutes! Store any extras in the freezer for breading chicken, fish, adding to meatloaf, or meatballs.

How to Make Healthier Broccoli Cauliflower Casserole

If the thought of this easy, cheesy casserole has your mouth watering, but you are wanting something a little healthier – here are some options for you to consider.

Use light mayonnaise, or low-fat plain greek yogurt, in place of regular mayonnaise. You could also try avocado mayonnaise – I have not personally tried this, but believe it could work.
Use light sour cream instead of regular sour cream.
Substitute heavy cream with half and half, milk or non-dairy milk.
Omit the cereal topping to remove a few extra calories.
Reduce the amount of cheese covering the top of the casserole.

Tips and Tricks for Making Best Broccoli Cauliflower Casserole Recipe

For best tasting veggies, do not cook them fully initially. When parboiling, they should still be slightly crisp. The vegetables will finish cooking in the oven.
Use any preferred cheese in place of sharp cheddar.
Freshly grated cheese is best because it melts smoother. Packaged pre-shredded cheese contains an anti-caking ingredient could yield grainy results.
In place of a 2 quart casserole dish, use a 8X8 or 9X9 inch square pan, 11X7 baking pan, or 9X13 casserole dish. How deep the baking dish is will result in different baking times, so adjust accordingly. The bigger the pan, less baking time will be needed.
Frozen veggies can replace the fresh broccoli and cauliflower florets. You will need approximately 36 ounces frozen vegetables.

More Favorite Casserole Recipes

Tuna Noodle Casserole from Scratch – This homemade, classic recipe is cheesy with a crunchy potato chip topping, contains no condensed soup, and is easily adaptable to make gluten free.
Chicken Tetrazzini Casserole – Chicken Tetrazzini Casserole is the ultimate family favorite comfort food. Tender chicken, noodles, and sautéed mushrooms are tossed in a creamy wine sauce and topped with golden cheese.
Easy Cheese Grits Casserole – Easy Cheese Grits Casserole recipe is the perfect comfort side dish for breakfast, brunch, or even a weeknight dinner.
Mexican Tater Tot Casserole – Creamy seasoned ground beef is layered under golden crispy tater tots and lots of gooey melted cheese.

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Broccoli Cauliflower Casserole