Brussels Sprouts Au Gratin with Bacon

This creamy Brussels Sprouts Au Gratin combines hearty brussels sprouts with bacon and cheese for a comforting side dish that is naturally low carb. Serve this cheesy brussels sprouts casserole as a side for a weeknight meal or for Thanksgiving dinner!  

baked brussels sprouts casserole in a baking dish

Although there are many sides to love that are a classic part of Thanksgiving dinner, I have to say that brussels sprouts au gratin with bacon is one of my favorites. Who wouldn’t enjoy tender brussels sprouts mixed with a creamy cheese sauce and baked until the cheese is nice and bubbly? Nothing goes better with a perfectly cooked Thanksgiving Turkey

This brussels sprouts casserole starts with fresh brussels sprouts that are blanched until slightly tender. They are then mixed with a creamy sauce made of milk, cheese, and seasonings. Bake them up with salty bacon and cooked shallots for comfort food that pairs well with any meal.

This recipe also contains no breadcrumbs making it the perfect dish for anyone following a low-carb lifestyle! 

Why You’ll Love This Recipe

  • A great dish to serve at Thanksgiving, Christmas or any time. 
  • Uses nutrient-dense brussels sprouts that are healthy and packed with fiber. 
  • Made without breadcrumbs which keeps the carb count lower.
  • You can customize it to use your favorite cheeses or make it with or without bacon. 
  • It is gluten free with a simple modification.
all of the ingredients for brussels sprouts au gratin on a white countertop

Ingredients You’ll Need

  • Brussels Sprouts – You’ll need 2 pounds brussels sprouts that are trimmed and halved. Fresh is best. 
  • Bacon – Although optional, chopped bacon adds a salty bite and gives a great layer of flavor. 
  • Avocado Oil – Used to cook down the garlic, shallots, and bacon if not using bacon grease. 
  • Shallots & Garlic – Infuses the dish with garlic and a mild onion flavor. 
  • All-Purpose Flour – The thickening agent for the homemade cheese sauce. You can substitute with arrowroot powder, if desired.
  • Milk – Helps thin out the cheese to make a creamy sauce. You can substitute the milk for heavy cream or half and half, if needed.
  • Seasonings – You’ll need thyme, salt, and nutmeg to add flavor to the dish. 
  • Shredded Cheese – A mix of cheddar jack cheese and parmesan make the perfect blend to bake into the dish. 

Make this brussels sprouts recipe gluten free by using arrowroot powder to thicken the sauce instead of flour.

mixing together the brussels sprouts casserole in a skillet

How To Make Brussels Sprouts Au Gratin

  1. Prepare for baking: Preheat oven to 400 degrees Fahrenheit. Butter or spray with oil an 8×12 casserole dish and set aside.
  2. Blanch the brussels sprouts: Bring a large pot of salted water to a boil. Add the halved brussels sprouts for 3 to 5 minutes, until just barely tender. Remove from pot, drain, rinse with cold water and set aside.
  3. Prepare the bacon & shallots: If you’re using bacon in this dish, fry it in a large skillet until crispy. Remove and soak up excess oil on a paper towel, then chop it into small pieces. Set aside. Using the bacon grease, cook the shallots over medium heat until soft and translucent, then saute the garlic with the shallots for about one minute or until the garlic is fragrant. 
  4. Prepare the cheese sauce: Add the flour to the bacon grease, shallot, and garlic mixture and whisk for 1-2 minutes. Pour in the milk and whisk over medium heat until the sauce thickens and the milk is able to coat the back of a spoon. Add in the spices, then stir in the shredded cheese and stir until melted. Stir in ½ of the chopped bacon. 
  5. Assemble and bake the brussels sprouts casserole: Add the blanched brussels sprouts into the cheese sauce mixture and stir until fully coated. Pour the mixture into a prepared baking dish. Sprinkle remaining bacon and parmesan cheese on top, then bake for 20-25 minutes or until casserole has set and cheese is melted on top. Let cool for 10 minutes before serving. 
brussels sprouts casserole filling in a baking dish before baking

Recipe Tips

  • Use similar sized brussels sprouts. When purchasing fresh brussels sprouts, make sure they are all roughly the same size. You may need to quarter the larger brussels sprouts so they cook evenly. 
  • Don’t skipping blanching the brussels sprouts. It’s important to blanch the brussels sprouts before baking as this will help keep them tender and prevent them from being undercooked. 
  • Make it vegetarian. If you are not using bacon for this recipe, simply saute the shallots and garlic in olive oil or avocado oil instead. 
  • Cook everything in one pan. For one less dish to clean, cook the bacon and sauce in a cast-iron skillet instead of transferring it to a baking dish. Add the skillet straight to the oven for baking. 

TIME SAVING TIP: This brussels sprouts gratin can be assembled up to 24 hours in advance before baking.


  • Add more veggies. Add a boost of vegetables by adding sautéed mushrooms and bell peppers to the mix. Thr roasted brussels sprouts casserole tastes great with a variety of additional vegetables.
  • Add spicy flavor. Sprinkle the top with red chili flake for a pop of heat. 
  • Use breadcrumbs. If you’re not worried about carbs, sprinkle some panko breadcrumbs on top before baking for a delicious crunchy topping. 
  • Add fresh herbs. Add fresh herbs such as basil, rosemary, or oregano to the cheese sauce for additional flavor.
  • Use different cheese. Switch up the cheese by using Gruyere, pecorino romano, or asiago. 
  • Make it extra creamy. For a super creamy sauce, use heavy whipping cream instead of milk. 
baked brussels sprouts gratin in a casserole dish

Try this brussels sprouts casserole recipe for dinner tonight or save it for your Thanksgiving dinner menu! If you try it, let us know what you think by leaving a rating and comment below.

baked brussels sprouts casserole in a baking dish

Brussels Sprouts Au Gratin

Yield: 6
Prep Time: 10 minutes
Cook Time: 40 minutes
Total Time: 50 minutes
Brussels sprouts casserole is a simple side dish that is creamy and cheesy! It is lower carb and made without breadcrumbs.
5 from 3 votes


  • 2 pounds brussels sprouts, halved
  • 4 slices bacon
  • 1 tablespoon avocado oil or olive oil, (optional)
  • 3 shallots, thinly sliced (or 1/2 onion)
  • 3 cloves garlic, minced
  • 2 tablespoons all-purpose flour
  • 1 3/4 cup milk
  • 2 teaspoons kosher salt
  • 1/2 teaspoon thyme
  • pinch nutmeg
  • 1 cup shredded cheddar jack cheese
  • 1/4 cup shredded Parmesan cheese


  • Preheat oven to 400 degrees F. Butter or spray with oil an 8×12 casserole dish and set aside.
  • Bring a large pot of salted water to a boil. Blanch the halved brussels sprouts for 3 to 5 minutes, until just barely tender. Remove from pot, drain, rinse with cold water and set aside.
  • Fry bacon until crispy, 8-10 minutes. Remove from pan and set aside on a paper towel-lined plate. Chop when cool to the touch.
  • Add the shallots to the bacon grease and sauté 4 to 5 minutes until softened. (If little grease remains, add a tablespoon of avocado or olive oil. You can also drain the bacon grease and sauté the shallots in oil instead.) Add the garlic and sauté 1 minute until fragrant. Stir in the flour and whisk for 1 to 2 minutes.
  • Add the milk and stir until well incorporated. Cook over medium low heat for several minutes, stirring, until the sauce thickens and coats the back of your spoon. Add salt, fresh thyme, and nutmeg.
  • Add cheddar jack cheese to the sauce and stir until melted and incorporated. Add half of the cooked bacon back to the sauce. Season to taste.
  • Stir the Brussels sprouts into the cheese sauce, and then transfer them to the casserole dish. Sprinkle with the remaining bacon and Parmesan cheese.
  • Bake for 20 to 25 minutes until browned and bubbling.


Storing: Leftover brussels sprouts au gratin can be stored in an airtight container and stored in the fridge for 3-4 days before reheating and serving. 
Freezing: Due to the high water content in brussels sprouts, freezing then thawing will create a mushy texture and is not recommended.


Calories: 190kcal, Carbohydrates: 17.3g, Protein: 11.7g, Fat: 9.9g, Saturated Fat: 4.7g, Polyunsaturated Fat: 0.6g, Monounsaturated Fat: 2g, Cholesterol: 20.7mg, Sodium: 601.6mg, Potassium: 613.5mg, Fiber: 5.8g, Sugar: 3.7g
Course: Side Dish
Cuisine: American
Author: Ashley C.
If you try this recipe, don’t forget to leave a review below or share a photo and tag @spoonfulofflavor on Instagram.

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6 comments on “Brussels Sprouts Au Gratin with Bacon”

  1. These are so delightful! I have made them a couple of times and would make them weekly if I could find fresh sprouts in my region of the country year around! 
    I have yet to make them and have anyone say they didn’t like them. 

  2. Lovely side. Looks delicious. I have brussels in my fridge. I’m going to make this today. Thanks!

  3. I LOVE brussels sprouts. But my kids weren’t converted until I served this recipe! The delicious cheese makes ALL the yummy difference. Thanks for such an easy side dish. It’s perfect all autumn and winter long.

  4. Can this dish be frozen before baking?

    • Hi, April! I haven’t frozen this dish yet myself, but it should freeze perfectly fine before baking. If you try it, let us know. Enjoy!

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