There's something irresistibly cozy about a warm, cheesy baked dish that brings vegetables to life. This Broccoli Cauliflower Casserole Recipe transforms humble florets into a creamy, crunchy delight that's perfect for family dinners or potlucks.

The image shows a white square baking dish filled with a casserole that has a golden brown, crumbly topping layer covering creamy, white sauce-coated broccoli and cauliflower florets underneath. A black spatula with a wooden handle is lifting a portion of the casserole, showing the thick, creamy texture of the sauce and green broccoli mixed with white cauliflower below the crunchy topping. The dish is placed on a white marbled surface with a soft white cloth in the background. photo taken with an iphone --ar 2:3 --v 7

Jump to:

Why You'll Love This Recipe
Ingredients & Why They Work
Make It Your Way
Step-by-Step: How I Make Broccoli Cauliflower Casserole Recipe
Top Tip
How to Serve Broccoli Cauliflower Casserole Recipe
Make Ahead and Storage
Frequently Asked Questions:
Final Thoughts
Broccoli Cauliflower Casserole Recipe

Why You'll Love This Recipe

From the first time I baked this Broccoli Cauliflower Casserole Recipe, it quickly became one of my go-to side dishes. It's simple yet comforting, blending fresh veggies with a luscious cheesy sauce and a crisp topping you won't want to stop nibbling on.

Comfort in Every Bite: The creamy cheese sauce and tender veggies make it feel like a warm hug.
Simple Ingredients: You probably have most of what you need in your kitchen already, so no special trips needed.
Versatile Side Dish: It pairs beautifully with almost anything—from your Sunday roast to weeknight grilled chicken.
Make-Ahead Friendly: Prep in advance and bake just before serving, a lifesaver for busy days or holidays.

A close-up of a fork lifting a golden brown, crispy piece of macaroni and cheese topped with small green herb leaves, showing a creamy cheesy inside with a crunchy crumb layer on top. The dish is served on a white plate with decorative edges, placed on a white marbled surface; in the background, a white baking dish filled with more of the macaroni and cheese is visible but out of focus. A sprig of fresh thyme lies on the plate beside the macaroni. Photo taken with an iphone --ar 2:3 --v 7

Ingredients & Why They Work

Each ingredient in this Broccoli Cauliflower Casserole Recipe works in harmony to deliver rich flavor and satisfying texture. Using fresh broccoli and cauliflower is key—you want them tender but not mushy for that perfect bite.

Flat lay of fresh broccoli florets cut into 1-inch pieces, fresh cauliflower florets cut into 1-inch pieces, diced white onion, whole uncracked brown garlic bulbs alongside minced garlic cloves, a small white ceramic bowl of golden butter cubes, a small white ceramic bowl of all-purpose flour, a small white ceramic bowl of milk, fresh thyme sprigs, a small white ceramic bowl of coarse salt, a small white ceramic bowl of whole black peppercorns, shredded sharp cheddar cheese piled neatly, shredded parmesan cheese in a small mound, a small white ceramic bowl filled with plain bread crumbs, a small white ceramic bowl containing garlic powder, a small white ceramic bowl with melted butter, all arranged symmetrically and balanced on a clean white marble surface, soft natural light, photo taken with an iPhone, professional food photography style, fresh ingredients, white ceramic bowls, no bottles, no duplicates, no utensils, no packaging --ar 2:3 --v 7 --p awthu7i m7354615311229779997

Broccoli: Provides that vibrant green pop and a slightly earthy flavor; cut into 1-inch pieces for even cooking.
Cauliflower: Adds mildness and creamy texture, balancing the broccoli's sharper notes.
Butter: Builds the base of the creamy sauce and enriches the bread crumb topping.
Onion: Adds sweetness and depth when sautéed gently.
Garlic: A must for a savory punch, used both in the sauce and topping to layer flavors.
All-Purpose Flour: Essential for thickening the sauce to that perfect consistency.
Milk: Creates the creamy body of the sauce; whole milk works best but feel free to adjust.
Fresh Thyme: A little herbal brightness keeps the dish from feeling too heavy.
Salt & Pepper: Seasoning essentials to enhance every note.
Sharp Cheddar Cheese: Melts beautifully and brings bold, tangy cheese flavor.
Parmesan Cheese: Adds nutty richness and helps create a golden crust.
Bread Crumbs: Gives that much-loved crunchy topping that contrasts with the creamy veggies underneath.
Garlic Powder: Mixed into the topping for extra savory depth.

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Note: You'll find the complete list of ingredients, along with their exact measurements, in the printable recipe card at the bottom of this post.

Make It Your Way

One of the best things about this Broccoli Cauliflower Casserole Recipe is how easily it can be tailored to your preferences. I love to switch things up depending on what I have on hand or the season.

Variation: Sometimes, I add a handful of cooked, crumbled bacon on top before baking for a smoky, savory twist that everyone raves about.
Dietary Adaptation: For a lighter version, swap the butter for olive oil and use a mix of milk and a splash of vegetable broth.
Seasonal Swap: Feel free to toss in other sturdy veggies like carrots or green beans if you want to get creative with your produce.

Step-by-Step: How I Make Broccoli Cauliflower Casserole Recipe

Step 1: Prep and Cook Your Vegetables

Start by washing and cutting your broccoli and cauliflower into roughly 1-inch florets — that size cooks evenly while still maintaining a nice bite. Then, bring a large pot of water to a boil and cook the veggies for about 4-5 minutes until they’re just tender but not mushy. Draining them well is key to avoid a soggy casserole later. I like to toss them into a lightly greased 9x13 inch baking dish while they’re still warm so they hold their texture perfectly.

Step 2: Whip Up the Creamy Cheese Sauce

Next, melt butter in a large skillet and sauté your diced onions and minced garlic until they’re soft and fragrant — about 4 to 5 minutes. Then sprinkle in the flour and whisk constantly to form a smooth roux. Slowly pour in the milk, whisking the whole time until you get a creamy, thick sauce. Toss in fresh thyme, salt, and pepper for flavor. This sauce is what brings everything together, so take your time smoothing it out to avoid lumps.

Step 3: Combine and Top with Cheese and Crumbs

Pour the creamy sauce evenly over the warm broccoli and cauliflower in your baking dish, then sprinkle on the sharp cheddar and parmesan cheeses for that rich, melty goodness. For the topping, mix bread crumbs with melted butter and garlic powder, then spread it all over the surface to ensure a delightfully crispy crust after baking.

Step 4: Bake to Golden Perfection

Pop the casserole into your 350° oven and bake for 15 to 20 minutes until the top is golden brown and the filling is bubbling slightly around the edges. You want just the right amount of crisp on top with tender, flavorful veggies underneath — it’s the hallmark of a great casserole!

Top Tip

Over the years, I’ve learned that a few small tweaks make a big difference. Here are some tips to help you nail this Broccoli Cauliflower Casserole Recipe every time.

Don’t Overcook Your Veggies: They’ll finish baking in the oven, so stop just shy of tender to avoid a mushy mess.
Whisk the Roux Slowly: Stir the flour and butter mixture at a gentle pace before adding milk to prevent lumps forming in your sauce.
Use Fresh Thyme: Fresh herbs add a bright note that dried just can’t match, but if you only have dried, reduce the amount to avoid overpowering.
Let It Rest: After baking, let the casserole cool for a few minutes so it sets — this makes serving much easier and keeps slices intact.

How to Serve Broccoli Cauliflower Casserole Recipe

Broccoli Cauliflower Casserole - Serving Suggestion

Garnishes

I usually finish mine with a sprinkle of fresh parsley or chives for a pop of color and fresh flavor — it brightens up the cheesy richness perfectly. Sometimes, a few toasted pine nuts on top add a luxurious crunch that really impresses guests.

Side Dishes

This casserole pairs beautifully with roasted chicken, baked ham, or even a simple grilled steak. I often serve it alongside a crisp green salad to balance the creamy texture.

Creative Ways to Present

For special occasions, I like to serve this casserole in individual ramekins topped with fresh herbs and a drizzle of good olive oil. It feels so elegant and personal, plus your guests love digging into their own cheesy treasure.

Make Ahead and Storage

Storing Leftovers

Leftover broccoli cauliflower casserole stores great in an airtight container in the fridge for up to 3 days. I usually reheat it gently in the oven to keep that crispy topping from getting soggy.

Freezing

Freezing works too! Just cover the casserole dish tightly with foil or plastic wrap and freeze for up to 2 months. When ready, thaw overnight in the fridge before baking as usual.

Reheating

I find reheating in a 350° oven for 15-20 minutes keeps the texture closest to freshly baked. Microwave tends to make it watery or soggy, so I save that as a last resort.

Frequently Asked Questions:

Can I use frozen broccoli and cauliflower for this casserole?

You can, but fresh veggies tend to hold their texture better after baking. If using frozen, thaw and drain thoroughly to prevent excess moisture making the casserole soggy.

What if I don’t have fresh thyme?

Dried thyme is fine, just use about a third of the amount called for since dried herbs are more concentrated. Alternatively, a pinch of Italian seasoning works as a good substitute.

How do I make this casserole gluten-free?

Swap the all-purpose flour with a gluten-free flour blend or cornstarch for thickening. Also, make sure your bread crumbs are gluten-free or omit the topping and use crushed nuts for crunch instead.

Can I add protein to make this a main dish?

Absolutely! Adding cooked chicken, turkey, or even canned tuna can turn this side into a hearty main. Just mix in the protein with the veggies before adding the sauce, then proceed as usual.

Final Thoughts

I have to say, this Broccoli Cauliflower Casserole Recipe holds a special place in my kitchen rotation — it’s reliable, comforting, and endlessly adaptable. Whether you're making it for a casual weeknight or a festive gathering, you'll enjoy how it brings simple ingredients together with so much warmth and flavor. Give it a try; I’m sure it’ll become a favorite for you, too.