This extra-cheesy and luscious Brussels Sprouts Gratin is a must for Thanksgiving! Thinly sliced brussels sprouts are tossed in a cheesy gruyere sauce and topped with buttery bread crumbs.

The end result is an over-the-top cheesy and delicious gratin! Even the staunchest brussels sprouts skeptics will agree on how incredible this recipe is.

If you’re looking for a new and exciting way to serve brussels sprouts, this is it!

Brussels Sprouts Gratin

When I set out to create my Thanksgiving menu this year, I knew I wanted to include a brussels spouts recipe. What I didn’t expect was for this recipe to be an absolute hit that people raved over!

Brussels sprouts can be polarizing, but even veggie skeptics won’t be able to resist this ultra-cheesy and decadent casserole.

This brussels sprouts gratin is a deceptively simple recipe and only requires 9 ingredients! You can prep it in advance or throw it together last minute.

While this recipe is perfect served alongside Thanksgiving turkey, mashed potatoes, and gravy, you can just as easily serve it with roast chicken for an easy side dish.

Need more turkey day inspiration? Check out my collection of Thanksgiving recipes.

What is a Gratin?

A gratin—sometimes written as gratinée or au gratin—is a very flexible dish!

A gratin is always baked and/or broiled in a shallow dish. The topping is traditionally cheese or breadcrumbs, and they should get crispy under the broiler.“Gratin” is derived from the French verb gratiner—to broil.

While the most common gratin is potato gratin, it can really apply to any dish that fits that criteria. Technically even baked mac and cheese can be a gratin!

Regardless of how we define it, this brussels sprouts gratin is DELICIOUS.

How to Make Brussels Sprouts Gratin

I love making brussels sprouts gratin in a braiser or oven-safe skillet so that I can make everything in one pan that goes directly from stovetop to oven to table.

Tools Needed

• Braiser or Skillet
• Sharp Knife
• Cutting Board
• Mixing Bowl

Ingredients and Substitutions

• Brussels sprouts. I buy the pre-shredded sprouts but you can also shred them on a mandoline or with a sharp knife.
• Roux. This gratin is thickened with a roux made with butter and flour.
• Half and half. I love the richness that half and half adds. You could use whole milk if needed, but I think the extra fat makes all the difference.
• Shallot. I love the mellow onion flavor of shallots. You could also use yellow onion if needed.
• Garlic. Fresh garlic is a must!
• Cheese. A mix of gruyere and parmesan is the perfect blend of melty, salty, savory, and a bit nutty that pairs so well with the brussels sprouts.
• Dijon. A little bit of dijon adds great savory notes to the gratin.
• Nutmeg. A pinch of fresh nutmeg in the sauce is classic! You can omit it if desired.
• Breadcrumbs. I love using fresh breadcrumbs, but you can also use panko.

The Process

1. Make the roux. Melt the butter in an oven-safe skillet or braiser over medium heat. Add the shallots and garlic and cook for 2 minutes, until fragrant. Sprinkle in the flour and stir well to form a paste. Cook, stirring constantly, for 2 minutes to cook out the raw flour.
2. Make the sauce. Pour in the warmed half and half while whisking, until smooth. Bring to a gentle simmer while whisking until thickened. Add the dijon and nutmeg and stir well. Remove from the heat and stir in the gruyere and parm until melted. Season to taste with salt and pepper.
3. Make the breadcrumbs. Mix the breadcrumbs and parmesan together in a small mixing bowl and toss with the melted, cooled butter. Season with salt and pepper.
4. Assemble the gratin. Stir the shaved brussels sprouts into the cheesy bechamel sauce until everything is well-mixed and coated. Top with the breadcrumb mixture.
5. Bake. Transfer the skillet to the oven and bake for 20 minutes, until the top is browned and the cheese is melted and bubbly. Cool for 15 minutes before serving.

How to Make Fresh Breadcrumbs

Fresh breadcrumbs make all the difference in this brussels sprouts gratin and they couldn’t be easier to make. They add the perfect bit of crunch for a nice textural change.

Whenever I have bread that’s getting ready to go stale or that’s been hanging around for a bit, I make a batch of breadcrumbs to keep in the freezer.

Tear some pieces of bread into chunks and throw them into a food processor and run it until you have small crumbs. It’s THAT easy. Store in a freezer-safe ziplock bag in the freezer for up to 6 months.

How to Shave Brussels Sprouts

For shredding the sprouts, you can often buy them pre-shredded. This is my favorite hack for this recipe because it’s such a time-saver. You can find shaved brussels sprouts at HEB, Target, Sprouts, Trader Joe’s, etc.

You can also use a mandoline slicer, or you can use the shredding attachment on your food processor. Or, just a sharp knife will also do the trick. Make sure to trim any brown bits off the stem before thinly shredding.

Brussels Sprout Gratin Make Ahead Instructions

When you’re hosting a large dinner or event (especially Thanksgiving), I am definitely team prep ahead! Any recipe that can be made early will be made early so that the big day goes off without a hitch.

If you want to prep brussels sprouts gratin ahead of time, follow the recipe up until you stir the cheeses into the bechamel. Let the sauce cool for 15 minutes, then stir in the shaved brussels sprouts.

Transfer the mixture to a greased baking dish and cover tightly with plastic wrap. Refrigerate overnight. When it’s time to cook, top with the remaining cheese and the breadcrumbs and bake at 375 F for 25 minutes. Make sure the brussels sprouts gratin is warmed through.

Storage & Reheating Instructions

Leftover brussels sprouts gratin can be stored in an airtight container in the fridge for 3-5 days. I don’t recommend freezing leftovers as the veggies get mushy when defrosted.

I recommend reheating in the oven over the microwave to give the breadcrumbs some of their crispness back.

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This easy Brussels Sprouts Gratin is so cheesy and decadent. It’s perfect for your Thanksgiving table! If you do give this recipe a try, be sure to let me know! Leave a comment with a star rating below. Be sure to subscribe to my weekly newsletter and never miss a new recipe! You can also snap a photo & tag @JENNYGOYCOCHEA on Instagram. I LOVE hearing about & seeing your SMF creations!

More Thanksgiving Side Dish Recipes

Cranberry Sauce
Brioche Dinner Rolls
Baked Mac and Cheese
Horseradish Mashed Potatoes
Homemade Green Bean Casserole

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