Brussels Sprouts with Cheese Sauce

Name: Brussels Sprouts with Cheese Sauce
Prep time: 30 min
Cook time: 25 min
Total time: 55 min
Ingredients: 2 pounds Brussels sprouts (- steps and leaves removed); 1 head cauliflower (- broken into florets); 3 Tablespoons olive oil; kosher salt and freshly ground black pepper (- to taste); 3 Tablespoons unsalted butter; 3 cloves garlic (- minced); 3 Tablespoons all-purpose flour; 1 cup 2% milk; 1/2 cup heavy cream; 1/2 teaspoon dried thyme; kosher salt and freshly ground black pepper (- to taste); 1 1/2 cup gruyere cheese (- freshly grated)

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Brussels Sprouts with Cheese Sauce combines roasted Brussels sprouts and cauliflower with a creamy gruyere cheese sauce. A perfect holiday side dish that your family will love!

For other delicious Brussels sprouts recipes, try my Roasted Potatoes, Carrots, and Brussels sprouts, Teriyaki Brussels sprouts, or a reader fav Balsamic Glazed Brussels Sprouts and Sweet Potatoes.

Overhead shot of a casserole dish of roasted Brussels sprouts and cauliflower with gruyere cheese sauce.

Brussels Sprouts Recipe

On a normal daily basis, a simple dish of roasted Brussels sprouts is just fine. In fact, I occasionally make roasted veggies a full meal. But when holidays or special occasions come around, I try to elevate these vegetables.

Enter – Brussels Sprouts Gratin with Gruyere Cheese! Adding a cheese sauce that literally takes 10 extra minutes provides that special touch to a classic dish.

Why This Recipe Works:

Makes a great holiday dish. This casserole is perfect for any special occasion. We always have a veggie on our table and this one is amazing.
Combines healthy and decadence. The base of this recipe includes one of my favorite vegetables and we can’t get enough of these health little cabbages. The decadence comes in the creamy cheesy topping.
Easy Brussels sprouts casserole. There are three basic parts to this recipe. One, roast the veggies, two, make the cheese sauce, and three, combine the two and bake.

Side shot of a spoonful of Brussels sprouts with gruyere.

What You’ll Need:

For the roasted veggies:

Brussels Sprouts – I started with two pounds of Brussels sprouts, but it will be less after trimming them.
Cauliflower – One head of cauliflower.
Olive Oil – Necessary for roasting the veggies.
S&P

For the cheese sauce:

Butter – I use unsalted butter.
Garlic – Fresh garlic adds the best flavor to everything savory!
Flour – Used to thicken the sauce.
Dairy – A combo of 2% milk and heavy cream.
Seasonings – Thyme, salt, and pepper.
Cheese – 8 ounces of gruyere cheese required. So good!

How to make Brussels Sprouts Gratin:

Step 1
Prepare the veggies. Slice the stems off the Brussels sprouts and remove the outer leaves. Slice in half or fourths, depending on size. Then chop cauliflower into florets.

Step 2
Roast veggies. Place the Brussels sprouts and cauliflower on two baking sheets lined with parchment paper. Drizzle with olive oil, and sprinkle with kosher salt and freshly ground black pepper to taste. Roast until the veggies are fork tender and are slightly browned. (I use my convection oven when I roast veggies so I can get a nice crisp to them.)

Collage of 1) the raw Brussels sprouts and head of cauliflower, and 2) the chopped veggies in a bowl.

Step 3
Grate the cheese. Freshly grate the gruyere cheese. Using pre-shredded cheese will sometimes make the melting process difficult.

Step 4
Make the cheese sauce. In a medium saucepan, melt the butter. Add garlic and stir for about 30 seconds. Add flour and whisk until it’s well combined. Then add the milk and heavy cream, and bring to a simmer. You’ll see it thicken as you whisk.

Add seasonings – the thyme, salt and pepper. Remove from heat and stir in the gruyere cheese (reserving a bit for the top). Stir until completely melted.

Collage of 1) the shredded gruyere, and 2) the cheese sauce with the gruyere on top.

Step 5
Prepare casserole. Spoon the roasted veggies in a casserole dish. Top with the cheese sauce and bake for 20-25 minutes, or until sauce is melted.

Collage of 1) the roasted veggies, and 2) the roasted veggies with the gruyere cheese sauce on top.

Recipe FAQs:

Can Brussels sprouts gratin be made in advance?

Yes, you can prep it early. Prepare the gratin but don’t bake until right before serving. You’ll need to increase the bake time to about 45 minutes to get everything nice and hot. Cover with foil if the cheese starts to get too dark on top. Casserole leftovers are GREAT!

How do I prep Brussels sprouts?

To prep Brussels sprouts, trim the end off each one. Then remove the outer leaves. Slice them in half.

Should I par-boil Brussels sprouts before roasting?

It’s not required, but some people like to par-boil them first to make sure they get soft in the middle.

What is a gratin? A gratin is a technique in which an ingredient is topped with a browned crust, often using cheese or breadcrumbs, sometimes both. (Easy but fancy, right?)

The baked Brussels sprouts casserole with a wooden spoon.

Tips for Roasting Vegetables:

Chop veggies in similar size so that roasting time is accurate for the whole batch.
If mixing veggies, chop quicker cooking ones larger and slower cooking ones smaller.
Spray the baking sheet with spray (or line it with parchment paper).
Spread veggies in pan without crowding them. This will ensure they are roasted and not steamed.
Use a nice amount of olive oil (good fats!) and salt & pepper (or other seasonings you prefer).
Roast your vegetables until they are fork tender, and slightly charred.

Other Side Dishes:

Half of the Brussels sprouts casserole on a wooden tray.

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xoxo ~Sue