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Cauliflower Au Gratin

Our easy, cheesy cauliflower au gratin recipe will wow your holiday guests, but it’s fast enough to grace your weeknight table, too.

Easy Cauliflower Au Gratin Recipe

Roasted cauliflower becomes creamy, cheesy cauliflower au gratin when it’s topped with an easy, homemade Gruyére sauce. We love that this lower-carb side is fast enough for weeknights but goes beautifully with holiday fare, too. Serve it with Roasted Garlic Honey Baked Ham, our Beef Tenderloin, Pork Loin Roast, or go ultra-fancy and pair it with our Pistachio Crusted Pork Tenderloin with White Wine Dijon Sauce.

Cauliflower, Parmesan, Gruyère, olive oil, butter, breadcrumbs, shallot, garlic, flour, milk and spices in prep bowls

Roasted Cauliflower Au Gratin Ingredients

Cauliflower
Parmesan cheese
Gruyère
Extra-virgin olive oil
Salted butter
Panko breadcrumbs
Shallot
Garlic
All-purpose flour
Whole milk
Mustard powder, nutmeg, salt and pepper.

raw cauliflower florets being tossed with olive oil and salt in a baking dish

panko breadcrumbs being toasted in butter in a skillet

sliced shallots, garlic and butter in a skillet

milk being added to a skillet with butter, shallots, garlic and flour to make a roux

How To Make Cauliflower Au Gratin

Prep the cauliflower. And while you’re separating the florets, you might want to ponder how much you love cauliflower. That might mean you need to take a peek at our little list of the very Best Cauliflower Recipes.
Roast the cauliflower. Oil, salt and a 9 x 13-inch baking dish. 400 degrees. 10 minutes.
Toast the panko. Layering the flavors with all this roasting and toasting is what make ours the best cauliflower au gratin recipe, ever. Toast the panko in your favorite skillet with a bit of butter just until it is slightly browned. Set the toasted breadcrumbs aside. Fun fact: “gratin” means “to grate” which is a reference to the breadcrumb-topping of gratinéed dishes like this cauliflower au gratin.
Make the base of your cheesy, creamy Gruyère sauce. In that same skillet, cook the shallots and garlic. Add a little butter and sprinkle in some flour. This is a roux! It will make your cheese sauce thick and creamy.
Make it saucy!Whisk in the milk and whisk constantly for a bit while the sauce thickens. Keep stirring, and add mustard powder, salt, pepper, nutmeg, Parmesan, and Gruyère. When it all comes together and is all saucy and thick, pull it off the heat. Hey, that was easy!
Bake the cauliflower gratin! Pour that cheesy sauce over the cauliflower, then sprinkle evenly with the remaining ¼ cup Parmesan and ¼ cup Gruyère. Bake until it’s bubbling, and then dig in!

mustard powder, salt, pepper, nutmeg, Parmesan, and Gruyère being added to a roux in a skillet

cauliflower au gratin made with milk, Parm, Gruyère, butter, spices & shallot in a baking dish ready for the oven

cauliflower au gratin made with milk, Parmesan, Gruyère, butter, spices, shallot, fresh garlic and

cauliflower au gratin made with milk, Parmesan, Gruyère, butter, spices, shallot, fresh garlic and breadcrumbs

How To Store + Tips

Roasting the cauliflower before covering it with the sauce and breadcrumbs keeps this rich gratin recipe from getting watery. Don’t skip this step!
You can store leftover cauliflower au gratin in an airtight container in the fridge for up to 3 days, but it will be best when it’s fresh.
A few tips for making the creamy, cheesy gratin sauce turn out perfectly. Work slowly, but whisk constantly. If it feels like things are happening too fast, turn the heat down a bit. If it feels like nothing is happening, experiment with turning the heat up slightly. Do not use pre-shredded cheese, as it often has additives that make it less willing to melt smoothly into a cream sauce.
While this recipe isn’t necessarily healthy (it has perhaps too much butter and cheese to be considered straight up healthy), it is , alower-carb (even more so if you skip the bread crumbs!), and it’s a pretty delicious way to encourage kids to try vegetables.

cauliflower au gratin made with Parmesan & Gruyèred topped with toasted breadcrumbs being scooped out of a baking dish

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Cauliflower Au Gratin

April 11, 2024

Serves: 6
Prep Time: 10 min
Cook Time: 50 min
Calories: 392

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Ingredients

1 (2½ pound-head) cauliflower, cut into florets or 1 (24 ounce bag cauliflower florets)
3 tablespoons extra-virgin olive oil
1 teaspoon sea salt
5 tablespoons salted butter
½ cup panko breadcrumbs
1 large shallot, thinly sliced
2 garlic cloves, minced
3 tablespoons all-purpose flour
1¾ cups whole milk
2 teaspoons mustard powder
½ teaspoon freshly cracked black pepper
¼ teaspoon ground nutmeg
¾ cup freshly grated Parmesan cheese, plus more for serving
1 cup freshly grated Gruyère
1 tablespoon minced fresh flat leaf parsley, for serving (optional)

Method

Preheat the oven to 400°F with a rack in the center position.
Place the cauliflower florets in a 9 x 13-inch baking dish and toss with 2 tablespoons of the olive oil and ½ teaspoon of the salt. Roast for 10 minutes.
Meanwhile, melt 2 tablespoons of the butter in a medium skillet over medium heat. Add the panko and toss until coated. Cook, stirring occasionally, until panko is golden brown, 3-4 mins. Transfer to a small bowl and wipe out the skillet.
In the same skillet, heat the remaining 1 tablespoon of olive oil over medium heat. Once the oil is glistening, add the shallot and cook, stirring, until softened, about 3 minutes. Add the garlic and cook, stirring, until fragrant, about 1 minute more. Add the remaining 3 tablespoons of butter. Once the butter is melted, sprinkle with the flour and whisk until absorbed, about 1 minute. Slowly whisk in the milk and cook, whisking, until the sauce has thickened, 4 to 5 minutes. Add the mustard powder, remaining ½ teaspoon of the salt, pepper, nutmeg, ½ cup of the Parmesan, and ¾ cup of the Gruyère. Cook, whisking often, until the cheese has melted, 2 to 3 minutes. Remove the skillet from the heat.
Once the cauliflower has roasted for 10 minutes, remove the baking dish from the oven. Pour the cream mixture over the cauliflower, then sprinkle evenly with the remaining ¼ cup Parmesan and ¼ cup Gruyère. Return to the oven and bake until the sauce is bubbling and the cheese is lightly browned, about 25-30 minutes. Remove from the oven and let cool for about 10 minutes.
Top the gratin with the toasted panko and parsley, if using, before serving.