There's something truly comforting about a warm, cheesy veggie bake, and this Broccoli Cauliflower Casserole with Cheddar and Parmesan Topping Recipe fits the bill perfectly. The blend of tender florets with a luscious cheese sauce and a crisp, golden topping makes it a standout dish on any table.

The image shows a white square baking dish filled with a broccoli and cheese casserole topped with a golden brown breadcrumb layer. A black spatula with a wooden handle is lifting a portion from the dish, revealing bright green broccoli and soft white cauliflower pieces covered in creamy melted cheese under the crunchy crumb topping. The casserole surface is textured with a crunchy, toasted breadcrumb layer that covers the entire dish. The background and surface have a white marbled texture, and a soft white cloth is partly visible behind the dish. 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 with Cheddar and Parmesan Topping Recipe
Top Tip
How to Serve Broccoli Cauliflower Casserole with Cheddar and Parmesan Topping Recipe
Make Ahead and Storage
Frequently Asked Questions:
Final Thoughts
Broccoli Cauliflower Casserole with Cheddar and Parmesan Topping Recipe

Why You'll Love This Recipe

I remember the first time I made this broccoli cauliflower casserole: the whole family was hooked by the first bite. It's one of those dishes that manages to feel indulgent and wholesome all at once.

Perfect blend of textures: creamy sauce meets crisp, cheesy breadcrumb topping for a delightful contrast.
Vegetable-forward but kid-friendly: Even those wary of veggies will be reaching for seconds.
Simple ingredients, big flavor: Uses everyday pantry staples to create something special.
Easy to prepare ahead: Great for busy weeks or holiday sides that can be made in advance.

A close-up view shows a fork holding a bite of macaroni and cheese with a crispy, golden crumb topping and tiny green herb leaves scattered on it. The macaroni is creamy yellow with a crunchy golden layer on top. The bite is lifted over a white plate with a ridged edge, where the same dish with broccoli pieces and the crumb topping is visible. The background has a white marbled texture with blurred parts of the casserole dish and some green herbs. Photo taken with an iphone --ar 2:3 --v 7

Ingredients & Why They Work

This recipe shines because of the balance between fresh vegetables and the creamy, cheesy sauce that binds it all together. Each ingredient brings something important to the table—texture, flavor, or richness—making the final casserole irresistible.

Flat lay of fresh broccoli florets cut into 1-inch pieces, fresh cauliflower florets cut into 1-inch pieces, a small white ceramic bowl of diced raw onions, a small white ceramic bowl with peeled garlic cloves minced finely, a small white ceramic bowl of small yellow butter cubes, a small white ceramic bowl containing all-purpose flour, a small white ceramic bowl of whole milk, fresh thyme sprigs, a small white ceramic bowl of coarse salt, a small white ceramic bowl of whole black peppercorns, a small white ceramic bowl filled with shredded sharp cheddar cheese, a small white ceramic bowl with shredded parmesan cheese, a small white ceramic bowl of plain bread crumbs, a small white ceramic bowl with garlic powder, and a small white ceramic bowl with melted butter, all arranged symmetrically with realistic proportions placed 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: Fresh florets add a satisfying bite and vibrant green color; opt for firm heads without yellowing.
Cauliflower: Its mild flavor complements broccoli perfectly; make sure to cut into uniform pieces for even cooking.
Butter: Essential for sautéing aromatics and creating a silky roux for the sauce.
Onion: Adds sweetness and depth when softened gently.
Garlic: Gives the casserole that savory punch we all crave.
All-purpose flour: Thickens the sauce, so it coats veggies without being runny.
Milk: Creamy base for the cheese sauce; whole milk works best for richness.
Fresh thyme: Provides a subtle herbal note that elevates the dish.
Salt & pepper: Seasoning is key — don’t be shy with this to bring out all flavors.
Sharp cheddar cheese: Brings tangy sharpness and melty texture; freshly shredded for best melt.
Parmesan cheese: Adds a nutty finish that crisps beautifully on top.
Plain breadcrumbs: For the crunchy topping that contrasts the creamy interior.
Garlic powder: Boosts the topping’s flavor without overpowering.
Melted butter (for topping): Helps breadcrumbs brown perfectly with extra flavor.

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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 reasons I keep coming back to this broccoli cauliflower casserole with cheddar and parmesan topping recipe is how flexible it is. You can easily tweak things to suit your taste or dietary needs without losing the essence that makes it so comforting.

Vegetarian or Keto Variation: Swap breadcrumbs for crushed pork rinds for a low-carb twist that's still crispy and delicious.
Add Protein: I sometimes mix in cooked chicken or turkey to turn it into a more substantial main dish.
Herb swaps: If you don’t have fresh thyme, rosemary or sage can give a lovely earthy note.
Cheese replacements: Feel free to mix in Gruyère or mozzarella if you're after a milder melt.

Step-by-Step: How I Make Broccoli Cauliflower Casserole with Cheddar and Parmesan Topping Recipe

Step 1: Prep and Par-Cook the Veggies

Start by washing and cutting your broccoli and cauliflower into about 1-inch pieces—uniform sizes help them cook evenly. Bring a large pot of water to a boil, then blanch the florets for 4-5 minutes until they’re just tender but still hold their shape. Drain carefully and transfer to a lightly greased 9×13-inch baking dish. I like to steam sometimes to keep more nutrients intact, but boiling works well and is quick.

Step 2: Build a Creamy Cheese Sauce

While the veggies cool, melt butter in a large skillet. Add the diced onion and minced garlic, cooking gently until they soften and smell incredible—usually about 4-5 minutes. Next, whisk in the flour to form a thick paste and slowly add the milk, stirring constantly to avoid lumps. Keep whisking until the sauce turns smooth and creamy. Season with salt, pepper, and fresh thyme—this is where the flavor really develops.

Step 3: Assemble and Layer the Cheeses

Pour the cheese sauce evenly over the broccoli and cauliflower in your baking dish. Sprinkle the sharp cheddar and parmesan cheese on top—make sure you spread it out well so every bite gets some cheesy goodness.

Step 4: Make the Crunchy Topping

In a small bowl, combine plain bread crumbs with garlic powder and melted butter. Stir everything together until the crumbs are evenly coated. Then, sprinkle this mixture generously over the casserole to create that beautifully golden crust once baked.

Step 5: Bake to Perfection

Bake your casserole at 350°F (175°C) for 15-20 minutes, until the cheese is bubbly, the topping turns golden brown, and the veggies are tender. Watching that crust brown is always my favorite part—it means dinner’s almost ready!

Top Tip

From making this casserole several times, I’ve learned a few tricks that help it turn out perfect every time. These little nuggets of advice have saved me from soggy textures or bland flavors more than once.

Don’t overcook the veggies: Par-cooking broccoli and cauliflower until just tender prevents a mushy bake later on.
Whisk the sauce constantly: This keeps your cheese sauce silky, smooth, and lump-free.
Use sharp cheddar for flavor: Mild cheddar won’t have that punch; sharp cheddar is worth the little extra effort.
Toast breadcrumbs separately: If you want extra crisp topping, you can lightly toast the breadcrumb mixture before adding it to the casserole.

How to Serve Broccoli Cauliflower Casserole with Cheddar and Parmesan Topping Recipe

Broccoli Cauliflower Casserole - Serving Suggestion

Garnishes

I like to top mine with a sprinkle of freshly chopped parsley or chives—it brightens the rich flavors beautifully and adds a pop of color. Sometimes a tiny drizzle of balsamic glaze gives a surprising sweet tang that pairs so well with the cheese.

Side Dishes

This casserole shines as a side for roast chicken, grilled sausages, or even holiday ham. If you want to keep it vegetarian, a simple quinoa salad or crusty bread would round out the meal nicely.

Creative Ways to Present

For special occasions, try serving individual portions in ramekins, topped with that crisp breadcrumb crust. It makes each serving feel a bit more elegant and personal. You can also layer the casserole with different cheeses or swap cauliflower out for roasted Brussels sprouts to surprise your guests.

Make Ahead and Storage

Storing Leftovers

I usually cover leftover casserole tightly with foil or plastic wrap and store it in the fridge for up to 3 days. Just reheat it in the oven to keep the topping crisp, or microwave on lower power if you’re in a hurry.

Freezing

If you want to freeze this casserole, I recommend baking it first, cooling completely, then portioning into airtight containers. It freezes well for up to 2 months. When ready, thaw overnight and reheat in the oven until hot and bubbly again.

Reheating

To keep the breadcrumb topping crisp when reheating, I reheat uncovered in a 325°F oven for about 15-20 minutes. If microwaving, you can sprinkle extra breadcrumbs on top and briefly broil to revive the crunch.

Frequently Asked Questions:

Can I use frozen broccoli and cauliflower for this casserole?

While you can use frozen vegetables, fresh broccoli and cauliflower deliver better texture and flavor. If using frozen, thaw and drain excess moisture to prevent a soggy casserole.

How can I make this dish dairy-free?

You can substitute dairy-free milk (like almond or oat milk) and use dairy-free butter and cheese alternatives. The sauce may be slightly less creamy, so adjusting thickness with a little extra flour helps.

What can I serve with Broccoli Cauliflower Casserole with Cheddar and Parmesan Topping Recipe?

This casserole works well alongside roasted meats, grilled chicken, or as a hearty veggie side with a grain dish like quinoa or wild rice.

Can I prepare this casserole ahead of time?

Absolutely! You can assemble this casserole up to 48 hours in advance and keep it refrigerated. Bake just before serving, ensuring the center is bubbly and the topping is golden.

Final Thoughts

This Broccoli Cauliflower Casserole with Cheddar and Parmesan Topping Recipe feels like home on a plate. It’s one of those dishes I always come back to because it comforts and satisfies in ways a simple side can’t. I hope you’ll enjoy making and sharing it as much as I've loved perfecting it in my own kitchen.