If you grew up thinking Brussels sprouts were bland, mushy, or something you forced yourself to eat during the holidays, this recipe will change your mind.
These keto Brussels sprouts au gratin are everything a comfort food side dish should be. It’s rich, creamy, and cheesy. Instead of relying on potatoes like a traditional au gratin dish, this low-carb version lets roasted Brussels sprouts shine, so you can feel good about indulging.
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Even people who normally avoid Brussels sprouts end up going back for seconds because roasting transforms the flavor and brings out their natural sweetness. Plus, it creates those golden, crispy edges that pair perfectly with the melted cheese.
This is the perfect recipe for enjoying something that tastes incredibly indulgent while still fitting into a keto or low-carb lifestyle. That’s one of the reasons this recipe has become such a favorite in our house!
Another reason that it stands out is that it’s surprisingly easy to make. There’s no complicated technique, no specialty keto ingredients, and no long prep time. You’re basically roasting Brussels sprouts, mixing it together with a cheese sauce, and baking everything together until bubbly and golden brown.
So if you’re ready to see how easy it is to make these vegetables taste amazing, keep on reading, you’re nearly there!
Why You’ll Love These Brussels Sprouts Au Gratin
There are plenty of keto side dishes out there, but this one does an excellent job of finding that perfect balance between comfort and a genuinely satisfying flavor that doesn’t make you feel bad about eating it.
I’ve made this recipe so many times for friends and family to gauge their reaction, and one thing people always love to see most is that it completely transforms Brussels sprouts. If you’ve only ever had plain steamed or boiled Brussels sprouts before, there’s a good chance you weren’t that impressed. But roasting them gives them a crispy, caramelized exterior with a tender, naturally sweet inside.
Plus, it’s keto-friendly and naturally gluten-free, making it ideal for many diets and lifestyles. It’s easy to swap in your favorite cheeses, bulk it up with different proteins, or meal prep it to take some stress off a busy week ahead. There are so many reasons I love this recipe, and from the first bite, I’m sure you will too.
What Makes This Recipe Keto Friendly?
Among the many reasons this recipe works so well is that it’s naturally keto-friendly and gluten-free. The richness from the heavy cream and cheese, instead of starchy thickeners, keeps the carb count low while still creating that classic au gratin texture everyone loves.
Brussels sprouts are considered a low-carb vegetable because they contain fiber, which reduces their net carbs. They’re also packed with nutrients like vitamins C and K, and antioxidants, making them a more nutrient-dense option than many traditional starchy side dishes.
Classic gratin dishes often rely on potatoes, breadcrumb toppings, and flour-based sauces, all of which are red flags for a keto diet. This version skips all of those to better satisfy, making them ideal for your lifestyle. Brussels sprouts contain significantly fewer carbohydrates than potatoes, which means you can enjoy a generous serving while still staying within your daily carb goals. Yay!
So while this recipe absolutely tastes indulgent, it also fits beautifully into a keto meal plan by focusing on nutrient-dense vegetables, healthy fats, and low-carb ingredients that still deliver serious comfort-food flavor.
Ingredients You’ll Need
To make this recipe, you’ll need simple ingredients that are easy to find but together, still create incredibly rich flavor.
- Brussels Sprouts
- Fresh Garlic
- Heavy Cream
- Cheddar Cheese
- Parmesan Cheese
- Olive Oil
- Garlic Powder
- Nutmeg
- Salt & Pepper
Measurements for each ingredient, along with instructions for making Brussels Sprouts au Gratin, are in the printable recipe card below.
Printable Brussels Sprouts au Gratin Recipe Card
Ingredients
- 1 ½ lbs Brussels sprouts, halved
- 3 cloves garlic, minced
- 2 tbsp olive oil
- ¾ cup heavy cream
- 1 cup sharp cheddar cheese, grated
- 1 cup parmesan cheese, grated
- 1 tsp garlic powder minced
- ¼ tsp nutmeg
- salt and pepper, to taste
Instructions
- Preheat the oven to 400℉. Grease a 3-quart baking dish and set aside.
- Remove the stems and any yellow outer leaves of the Brussels sprouts. Cut the sprouts in half or any extra large sprouts into quarters.
- In a large mixing bowl, toss the Brussels sprouts with olive oil, minced garlic, salt, and pepper. Spread the Brussels sprouts on a baking sheet and roast in the preheated oven for about 15 minutes until they start to caramelize and can easily be pierced with a fork with a just a bit of resistance.
- Remove them from the baking sheet and put them back in the large mixing bowl. Add the heavy cream, ½ cup of cheddar cheese, ½ cup of parmesan cheese, garlic powder, and nutmeg. Season with salt and pepper. Stir well to combine.
- Pour the mixture into the 3-quart baking dish. Top with the remaining ½ cup of parmesan and cheddar cheeses. Bake at 400℉ for about 25 minutes until it is bubbly and the cheese is starting to brown.
Notes
- You can substitute the cheddar cheese with the cheese of your preference. Other good options would be gruyere or swiss.
- If the casserole is starting to brown too early, cover it with aluminum foil to finish baking.
Expert Tips for the BEST Brussels Sprouts au Gratin
The secret to truly incredible Brussels sprouts au gratin lies in their texture and flavor. You want tender Brussels sprouts with crispy, caramelized edges, and a rich, creamy sauce with an irresistible golden-brown top.
Choose the Right Sprouts
Start by choosing fresh Brussels sprouts that are firm, bright green, and similar in size. Smaller sprouts tend to be sweeter and less bitter than oversized ones, and choosing ones of even sizes will cook more consistently.
Tip: If some sprouts are much larger than others, cut them into quarters so everything roasts at the same rate.
Season Properly
One of the biggest mistakes people make with Brussels sprouts is under-seasoning them before roasting. Don’t be afraid to season generously with salt and pepper before they even hit the oven. As they roast, they will absorb these flavors and begin to season from within. This is an excellent way to start layering flavor into your dish.
When mixing them into the cheese sauce, be sure to season everything once more to add lots of flavor to each component of this dish.
Avoid Overcooking
This is another great tip, as it’s important to keep in mind that the Brussels sprouts will be cooked twice in this recipe. Once when roasting, and again when baked with the cheese sauce. Since they’ll continue to cook in the casserole dish, you only want them partially tender before adding the cream and cheeses. This keeps them from being mushy after baking.
As they’re roasting, you can check for doneness by piercing them with a fork or sharp knife. You should be able to pierce them but still have a little resistance, as if you’re cooking them ‘al dente’.
Choose Good Cheese
Freshly grated cheese can make a huge difference. Pre-shredded cheese contains anti-caking agents that can prevent it from melting smoothly into sauces. But buy a block of cheese and shred it at home for the best results.
Let it Rest
Finally, let the casserole rest for about 10 minutes after removing it from the oven. The sauce thickens slightly as it cools, making it easier to serve and allowing all the flavors to settle in.
Variations & Substitutions
While this recipe is already keto-friendly and gluten-free, you can make additional swaps for flavor and lifestyle needs while still keeping it delicious and comforting.
Cheese swaps are one of the easiest ways to change the flavor profile. Sharp cheddar provides bold flavor, but Gruyere adds a richer, more sophisticated depth. Swiss cheese works beautifully for a slightly milder casserole, while mozzarella adds extra creaminess. Try a combination of these cheeses along with the Parmesan, which is a must for its salty, nutty flavor, and see which combo is your favorite!
Try adding protein to turn this side dish into a complete meal. Crispy bacon, pancetta, Italian sausage, or roasted chicken all pair well with Brussels sprouts, making this a more filling and well-rounded dish.
For a vegetarian variation, consider adding sautéed mushrooms, caramelized onion, or spinach to the dish. These all enhance the recipe without overpowering it.
Need a dairy-free option? Substitute the heavy cream with full-fat coconut milk and use dairy-free cheese alternatives. The flavor will change slightly, but the casserole can still turn out creamy and satisfying.
Tip: Unsweetened almond milk mixed with nutritional yeast can also help add to that cheesy flavor while keeping carbs lower.
What to Serve with Brussels Sprouts au Gratin
Brussels sprouts au gratin is rich, cheesy, and incredibly satisfying, which means it pairs best with simple proteins and lighter side dishes that balance out the creaminess. Whether you’re serving it for a holiday dinner, weeknight meal, or keto-friendly feast, there are plenty of delicious pairing options. Try some of these favorite pairings from the list below:
- Roasted Meats (Thanksgiving turkey, Christmas ham)
- Steak
- Grilled Salmon
- Cauliflower Mash
- Roasted Vegetables
- Green Salad
Because this dish is so versatile, it can work as either a side dish or a main course, depending on what you serve it with. The key is balancing richness with fresh, roasted, or protein-focused dishes that complement the creamy texture rather than compete with it.
Make-Ahead Tips
This recipe is an excellent make-ahead dish to save you time when weeks get busy or the holidays are approaching. Since casseroles often taste better after the flavors have had time to meld together, that’s all the more reason to prepare this dish ahead of time.
The easiest make-ahead method is to roast the Brussels sprouts in advance. After trimming and halving them, roast until lightly caramelized, then cool completely before storing in the fridge.
When you are ready to bake, simply combine the cooked sprouts with the remaining ingredients in a casserole dish and pop it into the oven. Or, you can even assemble the entire casserole a day in advance. Cover it tightly and refrigerate, then pull it from the fridge about 20 minutes before baking to let it warm a bit before putting the cold dish in the oven.
For longer storage, you can also freeze the casserole. To freeze, assemble everything, but do not bake it. Wrap it tightly in plastic wrap and foil to prevent freezer burn, and store it in the freezer for up to 2 months. When ready to use, thaw overnight in the fridge, then bake as directed in the recipe card. It may need an extra 10-15 minutes if you are baking it straight from the fridge.
How to Store & Reheat Leftovers
To store leftover Brussels sprouts au gratin, allow the casserole to cool completely, then transfer any leftovers to an airtight container. Leftovers typically last about 3-4 days in the fridge.
When reheating, the oven is the best option for preserving the creamy yet crispy texture. Bake at 350ºF until heated through. The air fryer is another great option for reheating this dish.
Tip: Adding a splash of cream before reheating can help loosen the sauce if it has thickened too much in the fridge.
New Ways to Enjoy Leftovers
Leftover Brussels sprouts au gratin can easily be repurposed into entirely new meals! Stir leftovers into scrambled eggs for breakfast, add them to an omelet, or serve them alongside grilled chicken or steak for an easy second dinner. Some readers have even chopped the leftovers and mixed them into cauliflower rice or keto pasta dishes for extra flavor.
Because this dish is so rich and satisfying, you’ll want to enjoy every bit of it, and finding fun and exciting ways to incorporate this dish into your day makes mealtime even more enjoyable.
Brussels Sprouts au Gratin FAQs
Here we’ve addressed some common reader questions, but if you have any more, leave them in the comments below!
Why Are My Brussels Sprouts Bitter?
Brussels sprouts naturally contain compounds that can taste bitter, especially if they’re older or overcooked. Roasting helps reduce bitterness and bring out their natural sweetness. Smaller, fresh Brussels sprouts also tend to taste milder than oversized ones. And pairing them with rich ingredients like cheese and cream can also help to balance out any bitterness.
Can I Boil Brussels Sprouts For au Gratin?
While roasting is preferred because it creates crunchy, caramelized edges and a deeper flavor, boiling can work if you prefer softer sprouts, though it doesn’t bring out as much of the natural sweetness as roasting. If boiling, cook them until al dente, then drain them well and pat them dry before continuing with the recipe. This will keep them from adding excess liquid to the casserole, which can make it watery.
Can I Make Brussels Sprouts au Gratin Ahead of Time?
This casserole is a perfect recipe to make ahead of time. You can roast the Brussels sprouts ahead of time or fully assemble the casserole up to 24 hours before baking. It also freezes well for longer storage.
Can I Use Frozen Brussels Sprouts?
You can use frozen sprouts, but fresh Brussels sprouts will give you the best texture in this recipe. Frozen sprouts contain more moisture and may become softer after baking. If you are using frozen sprouts, thaw and drain them thoroughly before roasting to prevent a watery casserole.
How Do I Get the Top Golden Brown?
To get that nice crispy, golden-brown top, bake the casserole uncovered and move it to the top rack during the last few minutes of cooking. You can also broil it briefly, but watch carefully, as the cheese can go from brown to burnt very quickly.
Brussels Sprouts Made Delicious
If you’ve been looking for proof that Brussels sprouts don’t have to be boring, I think you’d agree with me if I said you’ve found it.
This recipe has everything you want in a comfort food side dish: crispy, creamy, and rich. Plus, you don’t have to feel so guilty about eating this since it’s full of veggies! This version keeps things low-carb and keto-friendly without sacrificing texture or flavor. That’s what makes this recipe so good for both weeknight dinners and special occasions.
It’s simple enough to throw together on a busy evening, but it also feels impressive enough for Thanksgiving, Christmas, Easter, or any holiday gathering where you want something warm and crowd-pleasing on the table.
If you do end up making this recipe, don’t be surprised if you find yourself wanting to make it regularly, especially during the colder months when everyone craves something cozy and comforting.
Looking For More Low-Carb Recipes?
If you enjoyed this keto Brussels sprouts au gratin, be sure to check out some of our other low-carb comfort food recipes below.
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