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Roasted Cauliflower Casserole

Roasting the cauliflower first gives this casserole incredible flavor, caramelized edges, and a nutty sweetness that you simply can't get from boiling. Finished with a creamy Parmesan cheese sauce and a crispy, buttery topping, it's an elevated side dish that's perfect for holidays, Sunday dinners, or anytime you want to make vegetables the star of the meal.
Print Recipe
Servings: 8 people
Ingredients Method Notes

Ingredients
  

  • For the Roasted Cauliflower
  • 1 large head cauliflower cut into florets
  • 2 tablespoons olive oil
  • 1 teaspoon garlic powder
  • 1 teaspoon smoked paprika
  • 1 teaspoon Italian seasoning
  • ½ teaspoon kosher salt
  • ¼ teaspoon black pepper
  • Creamy Cheese Sauce
  • 2 tablespoons butter
  • 2 tablespoons all-purpose flour
  • 1½ cups whole milk
  • ½ cup heavy cream
  • 1 teaspoon Dijon mustard
  • 1 cup shredded sharp cheddar cheese
  • ½ cup shredded Gruyère cheese
  • ½ cup grated Parmesan cheese
  • ½ teaspoon garlic powder
  • Salt and pepper to taste
  • Crispy Parmesan Topping
  • ¾ cup panko breadcrumbs
  • 2 tablespoons melted butter
  • ¼ cup grated Parmesan cheese
  • 1 tablespoon chopped fresh parsley
  • Garnish
  • Fresh thyme
  • Chopped parsley
  • Extra Parmesan

Method
 

  1. Roast the Cauliflower
  2. Preheat the oven to 425°F (220°C).
  3. Line a baking sheet with parchment paper.
  4. Toss the cauliflower florets with the olive oil, garlic powder, smoked paprika, Italian seasoning, salt, and pepper.
  5. Spread in a single layer.
  6. Roast for 25–30 minutes, turning once halfway through, until the edges are beautifully browned and the cauliflower is tender.
  7. Make the Cheese Sauce
  8. While the cauliflower roasts, melt the butter in a saucepan over medium heat.
  9. Whisk in the flour and cook for 1 minute.
  10. Slowly whisk in the milk and cream until smooth.
  11. Cook until slightly thickened, about 3–4 minutes.
  12. Stir in the Dijon mustard, garlic powder, cheddar, Gruyère, and Parmesan.
  13. Season with salt and pepper.
  14. Assemble
  15. Reduce the oven temperature to 375°F (190°C).
  16. Transfer the roasted cauliflower to a greased 9-inch baking dish.
  17. Pour the cheese sauce over the cauliflower and gently stir to coat.
  18. Add the Topping
  19. Mix together the panko, melted butter, Parmesan, and parsley.
  20. Sprinkle evenly over the casserole.
  21. Bake
  22. Bake for 15–20 minutes, until hot and bubbly.
  23. Broil for 1–2 minutes if you'd like an extra golden, crispy topping.

Notes

Gal Pal Tips

  • Roasting instead of boiling concentrates the cauliflower's natural sweetness and prevents a watery casserole.
  • Grate your own cheese for the smoothest, creamiest sauce.
  • Don't overcrowd the baking sheet—space allows the cauliflower to caramelize instead of steam.

Delicious Variations

🥓 Loaded Roasted Cauliflower

Mix in:
  • Crumbled bacon
  • Green onions
  • Extra cheddar cheese

🍄 Mushroom & Gruyère

Add sautéed mushrooms and swap the cheddar for additional Gruyère.

🌿 Herb Garden

Stir fresh thyme, rosemary, and parsley into the cheese sauce for a fresh, aromatic flavor.

🌶 Southwest Style

Use Pepper Jack cheese, add diced green chiles, and finish with cilantro and a pinch of chili powder.

🧄 Roasted Garlic

Blend roasted garlic cloves into the cheese sauce for a rich, mellow garlic flavor.

What to Serve With It

  • Bourbon Glazed Salmon
  • Herb-Roasted Chicken
  • Prime Rib
  • Grilled Steak
  • Pork Tenderloin
  • Holiday Turkey
  • Baked Ham

Storage

  • Refrigerator: Store covered for up to 4 days.
  • Freezer: Freeze before or after baking for up to 2 months.
  • Reheat: Bake at 350°F until warmed through, or microwave individual portions.

Gal Pal Serving Tip

Serve this casserole straight from the oven with a sprinkle of fresh thyme, chopped parsley, and an extra dusting of Parmesan. The roasted cauliflower adds a rich, nutty flavor that pairs beautifully with the creamy cheese sauce and crunchy topping, making this a side dish guests will ask for again and again.