Brussels Sprouts au Gratin is a healthier twist on the classic potato dish. Brussels sprouts are mixed with a buttery, creamy sauce, topped with Gruyere cheese and breadcrumbs, then baked to toasty perfection. This simple, low-carb casserole side dish recipe is delicious for holidays like Thanksgiving or Christmas.
Brussels Sprouts au Gratin is the slightly healthier, lower-carb version of the starchy classic that we all know and love.
You still have all of the creaminess, cheesiness, and salty flavors you know – but you are actually getting a serving of green vegetables!
Even the Brussels sprouts naysayers will want to go back for seconds of this delicious casserole dish.
The secret is roasting the sprouts in the oven, so they get crisp and tender without becoming soggy.
A sprinkle of breadcrumbs at the end also gives a delightful crunch to counteract the creamy texture of the herb-packed sauce.
This recipe is a perfect side dish for holiday celebrations like Thanksgiving and Christmas. Or serve it up to make a normal weeknight feel a little fancier.
(You should also check out this Cauliflower au Gratin!)
Ingredients
To make this Brussels Sprouts au Gratin recipe you need:
- Brussels sprouts. This recipe calls for two bags of Brussels sprouts. Look for fresh sprouts with leaves that aren’t wilted.
- Oil. Avocado or olive oil will both work.
- Butter. Opt for unsalted butter. You can use vegan buttery sticks or coconut oil if needed.
- Garlic. Fresh, minced garlic is so important to add flavor to the cream sauce.
- Flour. All-purpose flour is great, or sub in a gluten-free 1-to-1 blend.
- Milk. Either regular or a plant-based alternative can be used interchangeably.
- Herbs. Fresh herbs, like tarragon and thyme, add so much flavor. If you use dried, be sure to reduce the amount used.
- Breadcrumbs. Panko-style adds a beautiful crunch to the casserole, but be sure to get a plain, unseasoned variety.
- Parmesan. Shredded Parmesan is mixed with the breadcrumbs for the topping.
How to Make Brussels Sprouts au Gratin
The basic steps for making Brussels Sprouts au Gratin are simple to follow:
Prepare the Brussels Sprouts
Preheat the oven to 400℉.
Use a sharp knife to cut off the ends of the sprouts. Be careful not to go too far past the stem. Remove any loose outer leaves.
Then, slice each one in half.
In a 7×10-inch baking dish, add the oil, ¾ teaspoon salt, and ¼ teaspoon black pepper. Add the Brussels sprouts and toss to coat.
Bake the veggies for about 15 minutes, being sure to flip them halfway through.
This extra step ensures they stay crispy, even with the sauce.
Make the Sauce
Melt the butter in a small sauce pan over medium or medium-low heat. Then, add the minced garlic and sauté for another 30 seconds.
Sprinkle the all-purpose or gluten-free flour over the melted butter and whisk well.
Add the milk slowly, in ¼ cup increments. Be sure to thoroughly mix the sauce after each addition. Allow it to thicken before pouring in more.
After the milk is fully incorporated, stir in the fresh thyme and tarragon along with the salt and pepper.
Put it Together
In a small bowl, combine the breadcrumbs, Parmesan cheese, and melted butter. Use a fork to mix it well, being sure to coat everything.
Carefully pour the cream sauce over the roasted Brussels sprouts. Sprinkle the Gruyere cheese first, and then top it with the Parmesan breadcrumb mixture.
Turn the oven down to 350℉. Bake the Brussels sprouts gratin for another 25 to 30 minutes. It is done when the crumbs are golden and crispy on top.
Let it rest for at least 10 minutes before serving. This allows the sauce to thicken.
Enjoy!
Meal Prep and Storage
- To Prep-Ahead: To save time, you can prep the Brussels sprouts a couple of days before, just leave them in the fridge until you’re ready. You can also make this dish in its entirety and just warm it up when you’re ready to enjoy it, but wait to add the cheese and breadcrumbs.
- To Store: Keep leftovers in an airtight container in the refrigerator for up to 4 to 5 days.
- To Freeze: While you can freeze this recipe, the Brussels sprouts might get soggy upon thawing. Be sure to completely cool before wrapping tightly and freezing for up to 6 months.
- To Reheat: This dish is best warmed up in the oven at 350℉. You can use the microwave, but it will be mushy.
Dietary Modifications
The recipe you’ll find below is already vegetarian as written. Here are some adjustments and substitutions you can make to help it fit your other dietary requirements:
- Gluten-free: Stick with a gluten-free 1-to-1 blend instead of all-purpose flour.
- Dairy-free: Use a dairy-free alternative for the milk, cheese, and butter.
FAQs
Brussels sprouts are a super-healthy, low-carb vegetable. One cup has around 4.5 net carbs.
Some recipes call for soaking this veggie before cooking. While this may help, it is definitely not necessary. Just be sure to thoroughly wash them first.
Some people have a variation of a particular gene that makes this sprout taste quite bitter. However, a creamy, flavorful recipe like this one is perfect to mask the bitterness if you taste it.
Expert Tips and Tricks
- Just the tip. Only cut off the end of the Brussels sprouts, avoid the leafy part.
- Clean ’em up. Remove the outer leaves if they’re wilted or falling off.
- Bake first. Roasting the Brussels sprouts before adding the sauce ensures they stay crispy.
- Get creative. If you don’t have thyme and tarragon, or just want a change, feel free to use different herbs.
- Make it early. This is an easy dish to meal prep ahead of time!
More Holiday Casserole Recipes
These holiday casserole recipes make entertaining a breeze:
- Sweet Potato Casserole
- Sweet Potato Casserole with Pecans
- Green Bean Casserole from Scratch
- Cajun Cornbread Dressing with Sausage
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Ingredients
- 2 lbs. Brussels sprouts
- 2 Tbsp. oil avocado or olive
- ¾ tsp. salt
- ¼ tsp. black pepper
- 2 Tbsp. butter
- 2 cloves garlic finely minced
- 2 Tbsp. flour or a gluten-free 1-to-1 blend
- 1 cup milk or a plant-based alternative
- 1 tsp. tarragon fresh, finely chopped
- 1 tsp. thyme fresh, finely chopped
- ½ tsp. salt to taste
- ¼ tsp. black pepper
- ¾ cup Gruyere cheese shredded
- ½ cup breadcrumbs Panko-style
- ¼ cup Parmesan cheese grated
- 2 Tbsp. butter melted
Instructions
- Preheat the oven to 400 degrees.
- Trim the ends from the sprouts and cut them in half. Add to a 7×10-inch baking dish along with the oil, ¾ teaspoon salt, and ¼ teaspoon black pepper. Toss until well coated. Bake for 15 minutes, flipping halfway through.
- Add butter to a small saucepan over medium heat. Once melted, add the garlic and continue sauteing for 30 seconds, or until fragrant.
- Sprinkle in the flour and whisk until combined.
- Slowly begin adding in the milk, ¼ cup at a time, whisking well after each addition.
- Once all of the milk has been added and the sauce has thickened, stir in the tarragon, thyme, salt, and pepper.
- In a small bowl mix together the breadcrumbs, Parmesan cheese, and melted butter.
- Pour the sauce over the roasted Brussels sprouts. Sprinkle with the Gruyere cheese and then the Parmesan-breadcrumbs.
- Reduce the oven temperature to 350 degrees and bake for 25-30 minutes, or until the crumbs are golden.
- Let sit for 10-15 minutes before serving so the sauce can thicken up. Enjoy!
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Notes
Meal Prep and Storage
- To Prep-Ahead: To save time, you can prep the Brussels sprouts a couple of days before, just leave them in the fridge until you’re ready to use them. You can also make this dish in its entirety and just warm it up when you’re ready to enjoy it, but wait to addd the cheese and breadcrumbs.
- To Store: Keep leftovers in an airtight container in the refrigerator for up to 4 to 5 days.
- To Freeze: While you can freeze this recipe, the Brussels sprouts might get soggy upon thawing. Be sure to completely cool before wrapping tightly and freezing for up to 6 months.
- To Reheat: This dish is best warmed up in the oven at 350℉. You can use the microwave, but it will be mushy.
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
