Cheesy Cauliflower Gratin — 🧀😋💛 Cauliflower florets are coated in a creamy cheese sauce and sprinkled with a crispy panko breadcrumb topping before being baked to golden, bubbly perfection! This is an EASY yet ELEGANT side dish that’s perfect for busy weeknights and holiday meals alike including Thanksgiving, Christmas, or New Year’s Eve!
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Easy Cauliflower au Gratin Recipe
Cauliflower gratin has everything I want in a great side dish — it’s quick to assemble, can be made with pre-chopped bags of cauliflower florets for even easier prep, and it’s packed with two types of cheese.
It’s a hearty casserole disguised as an elegant side dish. I mean, it’s essentially baked cauliflower with a creamy cheese sauce that’s presented in a pretty way. Not that I’m complaining whatsoever!
Any recipe that gets my whole family to eat their vegetables and takes just 15 minutes of active prep time to whip up is wonderful by me.
It’s a great weeknight dinner side especially when the weather turns chillier. But it’s also a wonderful side dish to add to your Thanksgiving, Christmas, or Easter dinner!
As written, the recipe comfortably feeds six people as a side dish, but you’re welcome to double the recipe if you’re expecting additional company this holiday season.
What Is Cauliflower au Gratin?
Cauliflower gratin is essentially a baked cauliflower cheese casserole that’s made with fresh cauliflower florets tossed in a creamy homemade cheesy sauce and covered with a crispy panko breadcrumb topping.
The term “au gratin” is French for “with a crust”.
Generally speaking, any dish with the label “au gratin” attached to it means it’s been topped with breadcrumbs and / or cheese and then baked.
Because I can’t resist cheese, and because I like to think of this as more of a special occasion side dish, I topped this easy cauliflower gratin recipe with both Gruyere AND Parmesan cheese.
Cauliflower Gratin Ingredients
Don’t let the “au gratin” title fool you into thinking this cauliflower cheese bake is in any way complicated or requires special ingredients. It’s actually the complete opposite!
You’ll need the following easy-to-find ingredients to make this recipe:
- Cauliflower florets
- Olive oil
- Seasoning salt – If you don’t have seasoning salt on hand, I would use 1-2 teaspoons kosher salt plus 1/2 to 1 teaspoon freshly ground black pepper
- Butter
- All-purpose flour
- Milk (whole milk is best)
- Salt
- Fresh thyme
- Grated nutmeg
- Gruyere cheese (or Swiss cheese)
- Panko breadcrumbs – AKA Japanese breadcrumbs; Do NOT use regular Italian-style breadcrumbs
- Grated Parmesan cheese
Note: Scroll down to the recipe card section of the post for the ingredients with amounts included and for more complete directions.
How to Make Cauliflower Gratin
This is a straightforward recipe, but there are few different steps to it. The cauliflower has to be roasted before being coated in the homemade creamy cheese sauce and then baked again together.
Here’s an overview of how this recipe comes together:
- On a baking sheet, toss the cauliflower florets with olive oil and season with seasoning salt. Bake at 425ºF for about 20 minutes.
- While the cauliflower bakes, make the cheese sauce.
- Add the roasted cauliflower pan to a 2-quart baking dish. Pour the warm cheese sauce over top.
- Combine the panko breadcrumbs with additional Parmesan cheese and sprinkle evenly over the cauliflower.
- Bake the au gratin cauliflower casserole at 375ºF until slightly golden and the edges are bubbling.
Recipe FAQs
If you didn’t roast the cauliflower prior to topping it with cheese sauce, it’s going to make the finished cauliflower gratin casserole watery. Cauliflower contains a lot of moisture, and roasting it removes most of the excess moisture.
Plus roasting provides that lovely roasted vegetable flavor which makes even ‘plain’ vegetables like cauliflower have more flavor and pizazz.
Also, the cauliflower in the gratin would be crunchy and half raw if you don’t roast it first, so don’t skip this step! Normally I am all about some crisp-tender veggies but this is a time where softer is better.
Any dish labeled as “au gratin” typically has a cheese and / or breadcrumb topping and is baked in a casserole dish.
If your cheese sauce curdled, you likely got it too hot. Although it probably didn’t start with the cheese; it probably started with the roux + milk. Make sure when you add the milk that you really watch the heat and don’t let it come up to any type of fast boil – just a simmer.
Then, after you add the two types of shredded cheese, also watch the heat. You need to cook over medium to medium-high heat to prevent it from curdling. And continue cooking just until the cheeses have melted and then immediately remove from the heat to prevent curdling.
The first thing to remember is to stir it constantly to prevent lumps. I like to use a wire whisk for this job. You should also remember to cook the cheese sauce at medium to medium-high heat, otherwise it will curdle and form lumps.
But the MOST IMPORTANT thing to do is to shred your own cheeses using a box grater. Pre-shredded cheese sold in a bag is coated in starch or another anti-caking agent which can make cheese sauces grainy or gloopy in texture. Buy an actual block of cheese and shred it yourself for the smoothest, creamiest cheese sauce for your cauliflower gratin recipe.
While you can sometimes find Parmesan already shredded in bags, it’s not super common. And I have never seen Gruyere sold like that so you need to shred it anyway. May as well just shred two blocks. Literally this is a 1 minute job per block, tops. 
I use 1 cup Gruyere cheese and 1/2 cup Parmesan in total for this recipe. I do recommend those two cheeses to preserve the elegant flavor and nice meltability they lend.
Gruyere is pricey, I know. However, it’s worth the splurge. The only real acceptable substitute is Swiss cheese. For the Parmesan, it’s really ‘go Parm, or go home’ here! I can’t think of any acceptable substitution.
This is one casserole that’s best enjoyed right away. You might be able to roast the cauliflower in advance, then make the cheese sauce day-of but I’m not 100% convinced that will be delicious and actually sounds like more work than it’s worth.
So, I suggest making the recipe as written on the day you plan on serving the cheesy cauliflower casserole. It will hold decently well at room temp for an hour or two so if you’re setting this out on a Thanksgiving buffet table, it’s fine if it’s not immediately consumed piping hot from the oven.
No, I do not recommend using frozen cauliflower to make cauliflower au gratin. Frozen cauliflower releases extra moisture in the oven and would likely end up being too mushy to suit the creamy cheese sauce.
Storage Instructions
In the fridge: Store for up to 5 days. Cover the pan with plastic wrap or transfer the leftovers to an airtight container to keep it fresh.
In the freezer: I don’t think the casserole would freeze well since it’s made with a cheese sauce and then you will have to contend with the potential mushy nature of frozen-and-thawed cauliflower.
To reheat: I reheat leftovers in the microwave, but you can also warm servings in a 350ºF oven in about 10 minutes.
What to Serve with Cauliflower Gratin
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Cheesy Cauliflower Gratin
Ingredients
- two 12-ounce bags cauliflower florets OR 1 large head of cauliflower, trimmed and cut into florets
- 2 tablespoons olive oil
- 1 to 2 teaspoons seasoning salt, or as desired
- 2 tablespoons unsalted butter
- 2 tablespoons all-purpose flour
- 1 ½ cups whole milk, 2% or half-and-half may be substituted
- ½ teaspoon salt, or to taste
- ½ teaspoon fresh thyme
- ¼ teaspoon ground nutmeg, optional* (See Notes)
- 1 cup Gruyere cheese, grated
- ½ cup panko bread crumbs, do not use regular bread crumbs
- ½ cup shredded parmesan cheese, divided
- Fresh parsley or fresh thyme, optional for garnishing
Instructions
- Preheat oven to 425F. If you have a convection oven, now is a great time to use it.
- If desired for easier cleanup, line a baking sheet with foil. Spray the baking sheet (or the foil on top of it) with cooking spray and evenly scatter the cauliflower florets. Tip – Make sure they are all actually bite-sized which is practical for both eating them and so that they all cook evenly.
- Roasting Cauliflower – Evenly drizzle with olive oil, evenly sprinkle with seasoning salt, and toss with your hands to combine and coat evenly. Tips – I use 2 teaspoons seasoning salt because cauliflower needs a lot of help in the salt department and you are flavoring a very large amount of a bland vegetable, but of course, season to taste. If you don't keep seasoning salt on hand, then I would use 1 to 2 teaspoons kosher salt and 1 teaspoon freshly ground black pepper, or to taste.
- Roast for about 20 minutes, or until golden browned around the tips and edges, and tender. Depending on their size and your oven, they may be done 5 minutes early, or 5 minutes later, so keep a watchful eye and check on them early. If desired, you can flip and toss them once midway through roasting for even cooking. Tip – While the cauliflower roasts, move onto the next steps so the sauce is ready when the cauliflower is done.
- Cheese Sauce – To a medium saucepan, add the butter and heat over medium heat to melt, about 1 minute; stir constantly.
- Once melted, sprinkle the flour over the butter and cook for 1 minute, or until sand colored; whisk constantly. This is called making a roux. Tip – Do not shortchange this step because the finished dish will both taste awful from the raw flour and the cheese sauce will be thin and runny.
- Slowly add the milk, salt, thyme, optional nutmeg, and cook for about 3 minutes, or until thickened; whisk constantly to avoid lumps and ensure even thickening.
- Add the Gruyere cheese, half the Parmesan, and heat until the cheese melts; whisk constantly. Take off the heat and set aside once melted and combined.
- Assembly – To a 1.7-quart baking dish (or similar sized baking dish) that's sprayed with cooking spray, add the cauliflower and smooth it evenly.
- Evenly pour the cheese sauce over the top.
- In a small bowl, combine the the panko breadcrumbs, remaining Parmesan cheese, stir to combine. And evenly sprinkle this mixture over the top of the cheese sauce.
- Baking – Reduce the oven heat to 375F (if you are using convection, reduce the heat to 375F convection) and bake for about 20 minutes, or until the top is lightly golden browned or as desired.
- Serving- Optionally garnish with fresh herbs and serve.
- Storage – Extra gratin will keep airtight in the fridge for 5 days. Reheat gently in the microwave as desired. I don't recommend freezing this dish due to the cheese sauce and the texture of the cauliflower will also change during the freezing/thawing process.
Notes
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
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