Broccoli Cauliflower Casserole – Cozy, Cheesy, and Weeknight Friendly

This Broccoli Cauliflower Casserole is the kind of dish that makes everyone at the table happy. It’s creamy, cheesy, and packed with tender veggies, without feeling heavy or fussy. You can serve it as a hearty side or a light main, and it fits right into a busy weeknight or a holiday spread.

Most of the work happens in the oven, and the ingredients are simple and familiar. If you’ve got broccoli, cauliflower, and a few pantry staples, you’re halfway there.

What Makes This Special

This casserole balances comfort with freshness. Broccoli and cauliflower get just tender enough to stay bright and a little snappy, while the sauce turns silky in the oven.

A crisp, golden topping adds texture that makes every bite better. It also adapts easily. You can keep it vegetarian, make it gluten-free, or add protein with leftover chicken or bacon.

The flavor is classic, but the method is straightforward and forgiving.

What You’ll Need

• 2 cups broccoli florets, cut into bite-size pieces
• 2 cups cauliflower florets, cut into bite-size pieces
• 2 tablespoons butter
• 1 tablespoon olive oil (optional, for richness)
• 1 small onion, finely chopped
• 2 cloves garlic, minced
• 2 tablespoons all-purpose flour (or gluten-free flour blend)
• 1 1/2 cups milk (whole or 2%; unsweetened almond milk works too)
• 1/2 cup sour cream or Greek yogurt
• 1 1/2 cups shredded sharp cheddar, divided
• 1/2 cup grated Parmesan, divided
• 1 teaspoon Dijon mustard
• 1/2 teaspoon smoked paprika (or regular paprika)
• 1/2 teaspoon kosher salt, plus more to taste
• 1/4 teaspoon black pepper
• 1/2 cup panko or breadcrumbs (use gluten-free if needed)
• 2 tablespoons chopped fresh parsley (optional, for garnish)
• Cooking spray or a little butter for greasing the baking dish

Instructions

1. Preheat the oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish or similar.
2. Par-cook the vegetables. Bring a large pot of salted water to a boil.

   Add the broccoli and cauliflower and cook for 2–3 minutes, just until bright and slightly tender. Drain well and set aside. Pat dry with a clean towel to avoid excess water in the casserole.
3. Sauté the aromatics.

   In a large skillet, melt the butter with the olive oil over medium heat. Add the onion and cook until soft and translucent, 4–5 minutes. Stir in the garlic and cook for 30 seconds until fragrant.

4. Make the sauce.

   Sprinkle the flour over the onion mixture and stir for 1 minute to cook off the raw taste. Slowly whisk in the milk, a little at a time, to avoid lumps. Simmer gently for 2–3 minutes until slightly thickened.

5. Enrich and season.

   Off the heat, whisk in the sour cream (or Greek yogurt), 1 cup of the cheddar, and 1/4 cup of the Parmesan. Add the Dijon, paprika, salt, and pepper. Taste and adjust seasoning.

   The sauce should be well-seasoned now.

6. Combine. Add the drained broccoli and cauliflower to the sauce and gently fold to coat. Transfer the mixture to the prepared baking dish and spread evenly.
7. Top it.

   In a small bowl, mix the panko with the remaining 1/2 cup cheddar and 1/4 cup Parmesan. Sprinkle evenly over the casserole.
8. Bake for 20–25 minutes, until the topping is golden and the edges are bubbling. If you want deeper color, broil for 1–2 minutes, watching closely.
9. Rest and serve.

   Let the casserole sit for 5–10 minutes to set. Sprinkle with parsley and serve warm.

Keeping It Fresh

Leftovers keep well for 3–4 days in an airtight container in the fridge. Reheat in the oven at 350°F (175°C) for 10–15 minutes to revive the crisp topping.

A quick reheat in the microwave works too, though the top won’t stay as crunchy. You can assemble the casserole a day ahead. Keep the breadcrumb-cheese topping separate, cover the dish, and refrigerate.

Add the topping just before baking so it stays crisp. For freezing, cool the baked casserole completely, wrap tightly, and freeze for up to 2 months. Thaw overnight in the fridge and reheat, covered, then uncover to re-crisp the top.

Benefits of This Recipe

• Vegetable-forward comfort: You get a full pan of veggies wrapped in a creamy sauce that still feels fresh.
• Flexible ingredients: Easy to adapt with different cheeses, add-ins, or dietary swaps.
• Make-ahead friendly: Assemble in advance and bake when you’re ready.
• Family-approved: Mild flavors with just enough tang and spice to keep it interesting.
• Great for gatherings: Doubles well, travels well, and reheats nicely.

Pitfalls to Watch Out For

• Overcooking the vegetables: If the broccoli and cauliflower are fully cooked before baking, they’ll go mushy.

  Keep the blanching short.

• Watery casserole: Drain and pat the veggies dry. Excess moisture thins the sauce and dulls the flavor.
• Undersalted sauce: The vegetables absorb seasoning. Taste the sauce before combining and make sure it’s flavorful.
• Gritty sauce: Cook the flour for a minute and add the milk gradually, whisking well to keep things smooth.
• Bland cheese: Use sharp cheddar or a blend with flavor.

  Milder cheeses can disappear in the oven.

Recipe Variations

• Gluten-free: Use a gluten-free flour blend for the roux and gluten-free panko. Everything else stays the same.
• Low-carb: Skip the breadcrumbs and finish with extra Parmesan for a crisp, cheesy crust.
• Bacon and cheddar: Fold in 1/2 cup cooked, crumbled bacon and a pinch of red pepper flakes.
• Chicken upgrade: Stir in 1–2 cups of shredded rotisserie chicken for a full meal in one dish.
• Extra veg: Add sliced mushrooms or sautéed spinach to the sauce before combining with the florets.
• Different cheeses: Try Gruyère for nutty depth, Monterey Jack for meltiness, or a little blue cheese for punch.
• Lighter version: Use Greek yogurt instead of sour cream and reduce the cheese by 1/2 cup. Add a squeeze of lemon for brightness.
• Herb-forward: Stir in fresh thyme or chives, or add a pinch of Italian seasoning to the sauce.

FAQ

Do I have to blanch the broccoli and cauliflower first?

Blanching helps control texture and prevents a watery casserole.

Raw florets can work, but they release more moisture and may cook unevenly, so the sauce can break or thin out.

Can I use frozen broccoli and cauliflower?

Yes, but thaw and drain them well, then pat dry. Frozen vegetables hold more water, so good draining is key to avoid a soggy bake.

What’s the best cheese for this casserole?

Sharp cheddar gives classic flavor and melts well. Adding Parmesan boosts savoriness.

For a twist, mix in Gruyère or Fontina for extra creaminess.

How can I make it dairy-free?

Use olive oil instead of butter, unsweetened plant milk, and a dairy-free yogurt for tang. Swap in a meltable vegan cheese or nutritional yeast to taste.

How do I keep the topping crispy?

Add the topping right before baking, and avoid covering the casserole during cooking. If reheating, uncover for the last few minutes or broil briefly.

Can I make this ahead?

Absolutely.

Assemble the base up to a day in advance, refrigerate, and top with the breadcrumb-cheese mixture just before baking. You may need a few extra minutes in the oven when baking from cold.

What size pan should I use?

A 9×13-inch dish works well. For thicker layers, use a slightly smaller casserole; for faster, thinner layers, use a larger pan.

Why did my sauce turn grainy?

It often happens if the milk is added too quickly or the heat is too high.

Keep the heat moderate, whisk steadily, and add the milk gradually to keep the sauce smooth.

In Conclusion

Broccoli Cauliflower Casserole brings together simple ingredients in a way that tastes cozy and fresh at the same time. It’s easy to prep, endlessly adaptable, and always welcome on the table. Whether you’re feeding a crowd or just want a reliable, veggie-forward bake for dinner, this one earns a spot in your regular rotation.

Keep the steps simple, season well, and enjoy that golden, bubbling top every time.