Brussels Sprouts Gratin (Low-Carb, Gluten-Free)

This dreamy, creamy Low Carb Brussels Sprouts Casserole is a delicious take on classic cheesy au gratin potatoes. A metric ton of flavor in one gorgeous, low-carb, gluten-free holiday side dish? Yes, please!

I don't do a lot of low-carb, keto or gluten-free recipes. But if you love entertaining, you're bound to love someone with dietary restrictions. This amazing recipe is my answer to just such a scenario.

Garlic, shallot and herb cream sauce is tossed over sliced Brussels sprouts and baked to a bubbling finish. Cheesy toasted almonds are layered over the top of the roasted Brussels and the whole glorious casserole comes to the the table with a flurry of diced chives and lemon zest.

This is my favorite way to add a gluten-free, low-carb side dish to every special occasion table. 

​What you need to make Brussels sprouts gratin:

Before we get to the step by step instructions, a few notes about the ingredients:

​Brussels: I've only made this recipe using fresh Brussels sprouts. Frozen sprouts hold a lot of water, so I don't recommend using frozen and thawed Brussels in this dish.

Cheese: substitute gruyere cheese for Parmesan for a similarly sophisticated topping. 

​Fresh herbs: thyme is an essential part of the cream sauce, but feel free to use diced flat leaf parsley in the almond topping if you want to skip the chives.

Full ingredient list and measurements included in the printable recipe card below.

How to make Brussels casserole:

Step 1: Make the Creamy Sauce

To begin, preheat oven to 400℉. Generously butter the inside of a 2-quart shallow baking dish. Set aside. 

Combine cream, sliced shallots, thyme leaves, garlic cloves, salt and pepper in a saucepan.

Bring to a gentle simmer over medium, then reduce heat and cook over low for about 12-15 minutes, until the shallots and garlic are soft. Use an immersion blender to mix the cream sauce until smooth, or transfer to a blender and pulse until the cream sauce is fully combined. 

Step 2: Prep Brussels

While the cream sauce is simmering, clean and cut your Brussels. Remove the core end and then slice into 3-4 pieces, about ¼ inch thick. Transfer sliced Brussels to the buttered baking dish. 

Step 3: Build the Casserole

Gently pour the garlic shallot cream sauce over the veggies and transfer to oven. Bake for 35 minutes, or until Brussels are tender. (Cook time will vary slightly based on how thick your Brussels are sliced. Test and leave in the oven longer, if needed.)

Step 4: Crunchy Almond Topping

While gratin is baking, make the crunchy almond parmesan topping. Combine toasted almonds, parmesan cheese, melted (and cooled) butter, chives and lemon zest in a small bowl. Toss to combine. 

Step 5: Finishing Touches

Once Brussels are tender, remove from oven. Sprinkle crunchy topping over the gratin and return to the oven for final 5-7 minutes until the topping is golden brown. (Keep an eye on the progress as almonds can brown quickly!)

Remove from oven and garnish with additional diced chives and lemon zest curls.

FAQs and Serving Suggestions

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