This recipe for brussel sprout casserole features sweet caramelized onions, tender roasted Brussels sprouts, and a cheesy sourdough topping. Savory and herbaceous, it’s the perfect elevated side dish for the holidays yet it's easy enough for a weeknight dinner!
Savory Brussel Sprout Casserole Recipe
Personally, I’m a huge fan of Brussels sprouts and don’t think they get the respect they deserve. I use them pretty much weekly in recipes like my crispy caramelized Brussels sprouts and Brussel sprout Caesar salad.
However, this Brussels sprout casserole is my all-time favorite way to use this winter veggie. Rich, subtly sweet, savory, herbaceous, and cheesy, it has everything you could want in a side dish and then some!
Truly decadent, it’s a staple on my holiday table and is so delicious even Brussels sprouts haters go back for seconds. Pair it with roasted turkey and all your classic sides, and you’ll have a gourmet meal everyone around the table will love.
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Brussels Sprouts Casserole Ingredients and Notes
- Olive oil - I prefer the strong flavor of olive oil for this recipe, but avocado oil will also work.
- White onions - I like to use white onions for a slightly tangier flavor, but yellow onions or sweet onions also taste great.
- Brussels sprouts - For the best results, use Brussels sprouts that have tight leaves and feel firm when squeezed. Slice them into halves or quarters before you begin.
- Coconut aminos - Adds depth and a salty, umami taste.
- Honey - A natural sweetener that balances the heaviness of the rest of the ingredients and helps the Brussels sprouts caramelize as they bake.
- Garlic - For the best flavor, use whole garlic cloves and mince them finely.
- Arrowroot Starch - Helps create a thicker filling.
- Beef broth - Use low-sodium beef broth. If needed, vegetable broth or bone broth can be substituted, but the flavor won’t be quite as rich.
- Thyme - For a vibrant, earthy flavor.
- Sourdough bread - You want to cut this into bite sized cubes so they can easily soak up all the delicious french onion flavors. Substitute croutons or breadcrumbs if needed.
- Gruyère cheese - A hard Swiss cheese, gruyère is salty, subtly sweet, and pairs wonderfully with the bold savory flavors of this dish.
How to Make This Recipe for Brussel Sprout Casserole
This is an overview with step-by-step photos. Full ingredients & instructions for this recipe are in the recipe card below.
Step 1: Create caramelized onions. Pour ¼ cup of the olive oil into a large skillet, and warm it over medium-low heat. Then, add the onions, and sauté until they’re caramelized. This takes about 45 minutes and requires continuous stirring!
Step 2: Prepare the Brussels sprouts. Toss the Brussels sprouts in a bowl with the remaining oil, coconut aminos, honey, and sea salt. Then, spread them out in an even layer on a baking sheet, placing them cut side down and leaving space between each piece. Bake until tender and browning, flipping the sprouts over halfway through cooking.
Step 3: Combine. Add the minced garlic to the skillet with the onions, gently stir to combine, and cook until fragrant. Then, add the arrowroot starch, mix to dissolve, and stir in the beef broth and thyme.
Step 4: Simmer. Transfer the roasted Brussels sprouts to the skillet, and gently mix them into the broth. Then, allow the pot to simmer for 2-3 minutes to infuse the Brussels sprouts with flavor.
Step 5: Top. Sprinkle the sourdough cubes and gruyère cheese on top. Then, bake until the bread is toasted, give everything a few big stirs then po pit back in the oven until the casserole is bubbling and the cheese is melted.
Step 6: Serve. Let the casserole set for at least 10 minutes. Then, enjoy warm!
Serving Suggestions
I love to serve this recipe for brussel sprout casserole as part of Thanksgiving dinner! Try pairing it with Thanksgiving turkey and your favorite side dishes for a complete meal.
Or, enjoy it as part of a fancy dinner with main courses like lemon baked salmon or cast iron beef tenderloin.
Frequently Asked Questions
Yes, you can prepare this dish up to a day in advance. To do so, caramelize the onions, roast the Brussels sprouts, and layer the ingredients, leaving off the breadcrumbs and cheese. Then, wrap the baking dish with foil, and transfer it to the fridge. When you’re ready to serve, bring the ingredients to room temperature, add the toppings, and bake as normal.
Leftovers will stay fresh in an airtight container in the fridge for up to 3 days.
Yes! If needed, you can freeze this recipe for up to 2 months. Thaw it in the fridge, and reheat it in the oven at 350F. The texture will be a bit softer, but it will still be tasty.
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Recipe
Brussel Sprout Casserole Recipe
Equipment
- 1 Mixing Bowl
- 1 (13 inch) Skillet or (8x12 inch) Baking Dish
Ingredients
- ¼ cup + 2 tablespoon olive oil
- 3 lbs white onions - approx. 6 large onion - sliced thinly
- 2 lbs brussel sprouts - halved or quartered if larger
- ½ tablespoon coconut aminos - or worcestershire sauce
- 2 teaspoon honey
- ¼ teaspoon sea salt
- 5 cloves garlic - minced
- 1 tablespoon arrowroot starch
- 2 cups beef broth - low sodium, you can also use vegetable or bone broth
- 1 tablespoon thyme
- 1 cup sourdough cubes - sub. croutons or breadcrumbs
- ⅔ cup gruyere cheese - grated
Instructions
- Preheat oven to 400 F. Pour ¼ cup of the olive oil into a large skillet and heat on medium low heat. Add the onions and saute until caramelized (this will take about 45 minutes and requires continuous stirring).¼ cup + 2 tablespoon olive oil, 3 lbs white onions - approx. 6 large onion
- Meanwhile, prepare the brussel sprouts by tossing them in a bowl with the remaining 2 tablespoon olive oil, coconut aminos, honey, and sea salt. Spread the brussel sprouts out on the baking sheet, cut side down, leaving some room in between each, and bake in the oven for 16 - 18 minutes, flipping the pan around half way through to ensure even browning. Set aside.2 lbs brussel sprouts, ½ tablespoon coconut aminos, 2 teaspoon honey, ¼ teaspoon sea salt
- Add the minced garlic to the skillet with the onions and gently stir into the onions. Allow it to cook until fragrant. Add the arrowroot starch to the onions and mix until dissolved. Add the beef broth and thyme to the skillet and stir.5 cloves garlic, 1 tablespoon arrowroot starch, 2 cups beef broth, 1 tablespoon thyme
- Transfer the roasted brussel sprouts to the skillet with onions and gently mix into the broth. Allow the pot to simmer for 2 - 3 minutes so the flavors infuse into the brussel sprouts.
- If not using an oven proof skillet, pour the mixture into an 8 X 12 inch baking dish. Sprinkle the sourdough cubes and gruyere cheese over top and bake for 5 - 7 minutes until the bread is golden and toasted. Take the skiller out of the oven and give it a few big stirs to incorporate the sourdough and cheese into the mixture then pop it back into the oven for another 7 - 7 minutes until the casserole is bubbling.1 cup sourdough cubes, ⅔ cup gruyere cheese
- Let the casserole set for at least 10 minutes before serving warm and enjoy!
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