Roasted Cauliflower Casserole with Sautéed Leeks and Pancetta
If you think cauliflower is boring, this Roasted Cauliflower Casserole is here to change your mind. Between the crispy pancetta, silky leeks, and creamy béchamel, this is the kind of cozy, impressive dish that feels fancy but is totally achievable at home. It’s rich, comforting, and exactly what you want when you’re craving something warm and savory!
If there’s one vegetable that truly shines when treated right, it’s cauliflower, and this casserole proves it! Roasting the cauliflower first gives it a deeper, slightly nutty flavor that steaming alone just can’t match. By the time it’s folded into a creamy béchamel with leeks and pancetta, it’s transformed into something so flavor-packed and delicious!
I also love this roasted cauliflower casserole with leeks and pancetta recipe because it walks that perfect line between side dish and main. It’s elegant enough to serve at a dinner party, but comforting enough for a quiet night in. And honestly, any recipe that combines roasted vegetables, cheese, and a classic sauce is going to be a winner in my book!
If you love using cauliflower in the kitchen like me, I recommend my roasted cauliflower and cannellini beans recipe or my Tandoori roasted cauliflower!
Why You’ll Love This Roasted Cheesy Cauliflower Casserole
- Deep, layered flavor. Roasting the cauliflower, crisping the pancetta, and gently cooking the leeks builds flavor at every step.
- Comfort food energy. Creamy béchamel, melted Swiss cheese, and a golden top make this feel rich and cozy!
- Flexible for entertaining. This cauliflower casserole can be prepped ahead and baked right before serving.
- Vegetable-forward but satisfying! While cauliflower is the star, the pancetta and cheese make it hearty enough to please everyone at the table.
Ingredients You Need
- Cauliflower: One medium head is perfect here. Cutting it into evenly sized florets ensures even roasting.
- Leeks: Use both the white and light green parts for the best flavor. Be sure to wash them thoroughly to remove grit!
- Pancetta: Adds salty, savory depth. Bacon works well as a substitute if needed.
- Swiss cheese: Melts beautifully and pairs perfectly with the mustard and béchamel.
- Olive oil: Helps the cauliflower roast evenly and develop color.
- Salt and black pepper: Essential for seasoning each layer of the dish.
- Béchamel sauce: The creamy backbone of the casserole. Homemade is best for flavor and texture, so feel free to use my béchamel sauce recipe!
- Dijon mustard: Adds subtle tang and cuts through the richness of the sauce.
Variations & Substitutions
- Make it vegetarian: Skip the pancetta and add sautéed mushrooms for umami to keep it vegetarian.
- Try a different cheese: Gruyère, fontina, or a sharp white cheddar all work beautifully.
- Add herbs: Fresh thyme or rosemary pair wonderfully with cauliflower and leeks.
- Swap the veg: Broccoli or Romanesco can be used in place of cauliflower!
How to Make Roasted Cauliflower Casserole with Leeks & Pancetta
- Preheat: Preheat the oven to 425F degrees.
- Roast the Cauliflower: In a baking dish add the cauliflower florets. Drizzle with olive oil and season with salt and black pepper. Roast the cauliflower for 20 minutes. (You can skip this step by blanching or steaming the cauliflower)
- Make the Sauce: In the meantime, make the béchamel sauce. (See my recipe) Add one tablespoon of Dijon mustard to the béchamel sauce and whisk to combine.
- Crisp the Pancetta: In a sauté pan add the pancetta and cook over medium high heat until crispy. Remove pancetta from the pan and set aside.
- Sauté the Leeks: Add leeks into the same skillet. Cook for 5-8 minutes on low heat until they turn soft. Add a splash of water if needed.
- Combine Everything & Bake: Combine béchamel sauce with 1/2 of the cheese, pancetta and leeks. Pour the sauce over the cauliflower. Add the rest of the cheese and bake in the oven for 35-40 minutes until golden. Enjoy!
Tips for Success
- Roast for extra flavor. Roasting the cauliflower adds depth that makes the final dish much more flavorful! However, if you are in a rush, you can quickly blanch the cauliflower, but this will add extra moisture to the casserole.
- Wash leeks well! Leeks trap dirt easily in between the layers. So slice and rinse thoroughly before cooking!
- Season every layer! Light seasoning at each step makes a big difference in the final result. Just be sure not to over salt, since pancetta is salty too.
- Let it rest. Allowing the casserole to cool slightly helps it set and makes serving easier!
Serving Suggestions
This roasted cauliflower casserole pairs beautifully with mains like a one pan pork loin or creamy mustard chicken. For a vegetarian meal, serve it alongside a salad like my charred romaine salad or warm lentil and kale salad. It would also be great with some homemade popovers!
Storage Suggestions
Store leftovers in an airtight container in the refrigerator for up to 4 days. This casserole can also be frozen, just wrap tightly and freeze for up to 2 months. Thaw overnight in the fridge and reheat in the oven until warmed through!
Frequently Asked Questions
This roasted cauliflower casserole with leeks and pancetta bakes for 35–40 minutes at 425°F, or until the top is golden and the sauce is bubbling around the edges. If you’re baking it straight from the fridge, you may need to add an extra 5–10 minutes to ensure it’s heated through.
Yes, this is a great make-ahead dish. You can fully assemble the casserole up to 24 hours in advance, cover it, and refrigerate until ready to bake. When baking from cold, allow a little extra time in the oven.
Roasting isn’t required, but it adds much deeper flavor and prevents the casserole from becoming watery. If you prefer, you can blanch or steam the cauliflower instead, just make sure it’s well drained before adding it to the sauce.
More Dinner Recipes to Try
- Creamed Kale Stuffed Acorn Squash
- Beef & Cabbage Gratin
- White Bean Sausage Cassoulet
- Bacon & Cabbage Gratin
- Savory Butternut Squash Invisible Cake
Roasted Cauliflower with Sautéed Leeks and Pancetta Casserole
Ingredients
- 1 medium head of cauliflower cut into florets
- 2 leeks with and green part, chopped, washed and drained
- 1 cup diced pancetta or 3-4 bacon strips
- 1 cup shredded Swiss cheese
- 2 tbsp olive oil
- Salt and black pepper to taste
- 2 cups
Béchamel sauce Béchamel Sauce – UncomplicatedChef - 1 tbsp Dijon mustard
Instructions
- Preheat the oven to 425F degrees.
- In a baking dish add the cauliflower florets. Drizzle with olive oil and season with salt and black pepper. Roast the cauliflower for 20 minutes. (You can skip this step by blanching or steaming the cauliflower)
- In the meantime, make the béchamel sauce. (See my recipe) Add one tablespoon of Dijon mustard to the béchamel sauce and whisk to combine.
- In a sauté pan add the pancetta and cook over medium high heat until crispy. Remove pancetta from the pan and set aside.
- Add leeks into the same skillet. Cook for 5-8 minutes on low heat until they turn soft. Add a splash of water if needed.
- Combine béchamel sauce with 1/2 of the cheese, pancetta and leeks. Pour the sauce over the cauliflower. Add the rest of the cheese and bake in the oven for 35-40 minutes until golden. Enjoy!
Video
Notes
- Roast for extra flavor. Roasting the cauliflower adds depth that makes the final dish much more flavorful! However, if you are in a rush, you can quickly blanch the cauliflower, but this will add extra moisture to the casserole.
- Wash leeks well! Leeks trap dirt easily in between the layers. So slice and rinse thoroughly before cooking!
- Season every layer! Light seasoning at each step makes a big difference in the final result. Just be sure not to over salt, since pancetta is salty too.
- Let it rest. Allowing the casserole to cool slightly helps it set and makes serving easier!
