Cauliflower gratin, rich, cheesy and comforting, is the perfect keto alternative to potato gratin.
It's ready in just 30 minutes, and the combination of sour cream, Dijon, gruyere and parmesan is absolutely marvelous.
As versatile as potatoes, cauliflower readily absorbs the richness of cream and cheese. It is thus elevated from merely a tasty veggie into a true delicacy.
Of all the many ways to prepare cauliflower, this creamy gratin is definitely one of my favorites. Granted, adding sour cream and gruyere cheese to almost anything would make it taste good! But this is especially true for cauliflower.
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Ingredients
You'll only need a few simple ingredients to make this tasty casserole. The exact measurements are included in the recipe card below. Here's an overview of what you'll need:
- Fresh cauliflower florets: Frozen cauliflower works too, but fresh is better in terms of flavor and texture.
- Sour cream: One time I experimented with whole-milk Greek yogurt and found that it was too tangy.
- Dijon mustard: Dijon is creamier and less vinegary than yellow mustard. I highly recommend using it in this recipe.
- Minced garlic: Mince it yourself, or use the stuff that comes in a jar. Both work, although freshly minced tastes better.
- Grated Gruyere cheese: This wonderfully nutty cheese is amazing. You can also use Jarlsberg or Raclette. Even a mild cheddar will work in a pinch.
- Kosher salt and black pepper: If using fine salt, you might want to reduce the amount you use, or the gratin could end up too salty.
- Grated Parmesan cheese: Make sure you use finely grated parmesan and not coarsely shredded.
Instructions
Making this keto cauliflower gratin is easy. The detailed instructions are listed in the recipe card below. Here are the basic steps:
- Your first step is to briefly steam the cauliflower. You can do it in the microwave. You should only microwave it until it's tender-crisp. You don't want it mushy.
- Next, mix the steamed cauliflower with a rich but quick sauce of sour cream, Dijon mustard, grated cheese, and spices.
- Then transfer the mixture to a greased baking dish and bake the gratin until golden and fragrant, about 10 minutes at 425°F.
Expert tip
If your baking dish is broiler-safe, you can finish the dish by briefly broiling it, to get the top nicely browned.
Frequently asked questions
A gratin is a baked casserole that's typically prepared in a shallow baking dish. It's topped with a topping (a "crust", hence the name "gratin") that gets browned when it is baked. The topping typically includes butter, cheese, and/or breadcrumbs.
No. Gratin is a baked dish. The very idea is to have a browned topping, and this can only be achieved by baking or broiling, not by microwaving. But you can definitely use the microwave to reheat the leftovers!
You can use broccoli. It's excellent, although the broccoli has a stronger flavor so the dish is not as similar to a potato gratin as one made with cauliflower.
Yes, although fresh does taste better and has a better texture. Defrost it according to the package instructions, taking care not to overcook it, and drain it really well before using.
Variations
I love this recipe as is and almost always make it as written. But in case you'd like to vary the basic recipe, here are a few ideas for you:
- As you can see, I season this dish very simply, with just salt and pepper. But you can add more spices if you'd like. Try adding a pinch of cayenne and a pinch of dried thyme.
- Top the gratin with bacon bits or crushed pork rinds before baking.
- If you can't find Gruyere cheese, sharp white cheddar works too.
Serving suggestions
This is such a versatile side dish. It truly goes with anything. But since I use a 425°F oven to make it, I like to serve it with a main dish that I can cook in the same oven. So I often serve this tasty gratin with one of the following main dishes:
Storing leftovers
You can keep the leftovers in the fridge, in an airtight container, for up to 4 days. Reheat them gently, covered, in the microwave on 50% power.
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Recipe Card
Keto Cauliflower Au Gratin
Ingredients
- 1 teaspoon butter for pan
- 1 lb. cauliflower florets
- 1 cup sour cream
- 1 teaspoon Dijon mustard
- 1 tablespoon minced fresh garlic
- ½ cup grated gruyere cheese (50 grams)
- 1 teaspoon Diamond Crystal kosher salt
- ½ teaspoon freshly ground black pepper
- 2 tablespoons grated Parmesan
Instructions
- Preheat your oven to 425 degrees F. Grease a shallow 1.5-quart baking dish with butter or olive oil.
- Place the cauliflower florets in a large microwave-safe bowl. Add a tablespoon of water. Cover with a microwave-safe plate and microwave on high until tender-crisp, 5-7 minutes.
- Meanwhile, in a large bowl, mix together the sour cream, mustard, garlic, gruyere, salt and pepper.
- Drain the cooked cauliflower well (careful, the bowl will be hot) and pat it dry. Add it to the sour cream sauce, gently tossing to combine.
- Transfer the mixture to the prepared baking dish. Sprinkle the Parmesan on top and bake until heated through, about 10 minutes. Serve immediately.
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Notes
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Nutrition per Serving
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Vered DeLeeuw, LL.M., CNC, has been following a low-carb real-food diet and blogging about it since 2011. She's a Certified Nutrition Coach (NASM-CNC), has taken courses at the Harvard School of Public Health, and has earned a Nutrition and Healthy Living Certificate from Cornell University. Her work has appeared in several major media outlets, including Healthline, HuffPost, Today, Women's Health, Shape, and Country Living. 
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