Brussels Sprouts Casserole

What happens if you take the classic green bean casserole and swap in Brussels sprouts? You get this Brussels Sprout Casserole!

Tender sprouts are coated in a rich, savory mushroom gravy and then topped with crispy shallots.

Plus it’s gluten-free, dairy-free, vegan, Paleo, keto and Whole30-friendly.

It’s the perfect dish no matter who is at your table, no matter if they have dietary restrictions or not.

Brussels Sprouts Casserole in a glass dish on a wooden table, one with a white plate with some casserole on it

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Brussels Sprouts Casserole

I know some people love green bean casserole but let’s face it, the green beans are kinda awkward to eat when packed onto your Thanksgiving plate.

Brussels sprouts are smaller and naturally bite-sized so they’re the perfect substitute.

For the gravy, we’re taking out all the dairy, weird thickeners, additives and starches and replacing them with lots of caramelized veggies and seasonings for flavor. To thicken it, we’re using arrowroot powder (read more about using arrowroot here).

Plus without dairy, this is a vegan Brussels sprout casserole.

And by using only low-carb veggies and just a small amount of arrowroot, it’s a keto Brussels sprout casserole as well.

And to pump up the flavor, we’re using both fresh and dried mushrooms. This ain’t no bland cream of mushroom soup mix! You can choose whichever mushrooms you like.

For the dried mushrooms, I honestly go with whichever option is the cheapest. At my store, that usually means hen of the woods or oyster.

For the fresh, I tend to go with pre-sliced baby bellas for convenience and flavor. If you all have are white button mushrooms, that’s fine! Just be sure to really brown them in the skillet to create as much flavor as possible.

Brussels Sprouts Casserole in a glass dish on a wooden table

 

What you need to make this Brussels sprouts casserole

Ingredients:

  • 1 oz. dried mushrooms
  • 1 tablespoon + 1 1.4 teaspoon fine sea salt, plus more if necessary
  • 1 1/4 – 1.5 pounds (20-24 oz.) Brussels sprouts
  • 1.5 tablespoons avocado oil
  • 2 large shallots
  • 2 garlic cloves
  • 8 oz. sliced fresh mushrooms
  • 2 cups low-sodium vegetable broth
  • 1 tablespoon arrowroot starch/flour
  • 1.5 teaspoons apple cider vinegar
  • 3/4 teaspoon dried thyme
  • 3/4 teaspoon dried sage
  • 1/2 teaspoon pepper
  • 1/2 cup cooking fat, such as palm shortening or avocado oil

To clean mushrooms: gently swipe off the dirt with a damp paper towel. If you rinse or soak them they’ll absorb too much water and get soggy.

Equipment:

Brussels Sprouts Casserole in a glass dish on a wooden table, one with a white plate with some casserole on it

How to make Brussels Sprouts Casserole

In a small/medium bowl, cover the dried mushrooms with very hot water and let soak for 30 minutes, stirring occasionally. Lift them out of the water (if you drain them, the sediment in the bottom of the bowl will just get poured over the mushrooms).

Wrap them up in a large piece of cheesecloth, flour sack towel or paper towels, and squeeze to remove as much water as possible. Roughly chop them and set aside.

Heat the oven to 350°.

Meanwhile, bring a medium saucepan 2/3 full of water to a boil over high heat. Add 1 tablespoon salt and stir to dissolve.

While the water is heating up, trim the root ends off the sprouts, leaving the leaves intact (save any that fall off if they’re clean). Halve them through the root. Quarter the large ones and leave the tiny ones whole.

Add the sprouts (and any separate leaves if they’re clean) to the water and cook (don’t wait for the water to come to a boil again) for 4 minutes if you’d like them al dente, 5 minutes if you’d like them a bit softer.

Drain thoroughly, tossing the sprouts around in the colander to remove as much water as possible.

To make the gravy, heat the avocado oil in a 10″ nonstick skillet over medium heat. Peel and dice one shallot. Peel and mince the garlic. Add them to the hot oil with 1/2 tsp. salt and saute, stirring occasionally, until softened and just starting to turn golden, about 5 minutes.

Add the sliced mushrooms and another 1/2 teaspoon of salt. Saute until deep brown on both sides, stirring occasionally. The skillet might not seem big enough but the mushrooms will shrink. Just make sure the mushrooms make contact with the skillet and most of the moisture has evaporated, about 8-10 minutes.

Add the mushroom and shallot mixture to a blender. Add the chopped dried mushrooms, broth, arrowroot, vinegar, thyme, sage and pepper. Blend until smooth. Taste and add more salt or seasonings if necessary. (If it seems a bit too salty, that’s okay. The flavor will dilute a bit as it bakes.)

Add the sprouts to an 8×8″ baking dish. Pour the mushroom gravy all over them. Toss the sprouts around a bit to make sure the gravy gets to the bottom. Bake for 20 minutes.

While the sprouts are baking, heat the palm shortening or avocado oil in a small saucepan over medium-high heat. Peel the second shallot and slice into thin rings. Cook the rings in the fat until golden brown, about 3-5 minutes (keep an eye on them, they go from brown to black very fast). Remove with tongs or a slotted spoon to a plate lined with paper towels to drain. You may need to cook them in batches.

Distribute the shallots over the top of the casserole and serve immediately.

Substitutions and variations

  • You can double the recipe using a 9×13″ baking dish and baking it for 30-35 minutes. However, triple the shallot topping (doubling won’t be enough).
  • No fresh garlic? Add 1/2 teaspoon garlic powder to the blender before blending the gravy.
  • Want to use fresh thyme and/or sage? That’s great! Use 2 1/4 teaspoons minced fresh herbs in place of the dried.
  • You can use lemon juice in place of the apple cider vinegar.
  • You can use chicken broth but then it won’t be vegan.

Make Ahead Instructions

The mushroom gravy can be made up to 3 days in advance. Blend or whisk in a little more water or broth if it’s too thick. The gravy can also be frozen for up to 3 months. Thaw overnight in the fridge.

The cooked casserole (without the shallot topping) can be refrigerated for up to 3 days. Toss everything again if necessary (the gravy might get watery but it’ll blend again) and bake at 350 degrees for 30-40 minutes to reheat. Proceed with the shallot topping.

 

Other recipes you might like:

  1. Sausage, Sweet Potato and Apple Stuffing (Paleo, Whole30)
  2. Date and Orange Cranberry Sauce (Paleo, Whole30)
  3. Balsamic Roasted Green Beans, Brussels Sprouts and Dates (Paleo, Whole30)
  4. Braised Red Cabbage (Paleo, Whole30)
2 images of Brussels Sprouts Casserole in a glass dish on a wooden table, one with a white plate with some casserole on it
Brussels Sprouts Casserole in a glass dish on a wooden table
Print Recipe
5 from 14 votes

Brussels Sprouts Casserole

Brussels sprouts are a great, bite-sized substitute for green beans in this paleo, vegan, keto and Whole30 casserole. And two kinds of mushrooms means the creamy gravy is packed with savory, umami flavor.
Prep Time30 mins
Cook Time35 mins
Total Time1 hr 5 mins
Course: Side Dish
Cuisine: American
Keyword: brussels sprouts, garlic, mushrooms, shallots
Servings: 4 servings
Author: Don Baiocchi

Ingredients

  • 1 oz. dried mushrooms of your choice
  • 1¼-1½ pounds (20-24 oz.) Brussels sprouts
  • 1 tablespoon + 1¼ teaspoons fine sea salt, divided, plus more as necessary
  • 2 large shallots, divided
  • 2 garlic cloves
  • tablespoons avocado oil
  • 8 oz. sliced mushrooms, like baby bellas
  • 2 cups low-sodium vegetable broth
  • 1 tablespoon arrowroot starch/powder/flour
  • 1.5 teaspoons apple cider vinegar
  • 3/4 teaspoon dried sage
  • 3/4 teaspoon dried thyme
  • 1/2 teaspoon ground black pepper
  • 1/2 cup cooking fat such as palm shortening or avocado oil

Instructions

  • In a small/medium bowl, cover the dried mushrooms with very hot water and let soak for 30 minutes, stirring occasionally. Lift them out of the water (if you drain them, the sediment in the bottom of the bowl will just get poured over the mushrooms). Wrap them up in a large piece of cheesecloth, flour sack towel or paper towels, and squeeze to remove as much water as possible. Chop them and set aside.
  • Heat the oven to 350°.
  • Meanwhile, bring a medium saucepan 2/3 full of water to a boil over high heat. Add 1 tablespoon salt and stir to dissolve.
  • While the water is heating up, trim the root ends off the sprouts, leaving the leaves intact (save any that fall off if they're clean). Halve them through the root. Quarter the large ones and leave the tiny ones whole.
  • Add the sprouts (and any separate leaves if they're clean) to the water and cook (don't wait for the water to come to a boil again) for 4 minutes if you'd like them al dente, 5 minutes if you'd like them a bit softer.
  • Drain thoroughly, tossing the sprouts around in the colander to remove as much water as possible.
  • To make the gravy, heat the avocado oil in a 10" nonstick skillet over medium heat. Peel and dice one shallot. Peel and mince the garlic. Add them to the hot oil with 1/2 tsp. salt and saute, stirring occasionally, until softened and just starting to turn golden, about 5 minutes.
  • Add the sliced mushrooms and another 1/2 teaspoon of salt. Saute until deep brown on both sides, stirring occasionally. The skillet might not seem big enough but the mushrooms will shrink. Just make sure the mushrooms make contact with the skillet and most of the moisture has evaporated, about 8-10 minutes.
  • Add the mushroom and shallot mixture to a blender. Add the chopped dried mushrooms, broth, arrowroot, vinegar, thyme, sage and pepper. Blend until smooth. Taste and add more salt or seasonings if necessary. (If it seems a bit too salty, that's okay. The flavor will dilute a bit as it bakes.)
  • Add the sprouts to an 8x8" baking dish. Pour the mushroom gravy all over them. Toss the sprouts around a bit to make sure the gravy gets to the bottom. Bake for 20 minutes.
  • While the sprouts are baking, heat the palm shortening or avocado oil in a small saucepan over medium-high heat. Peel the second shallot and slice into thin rings. Cook the rings in the fat until golden brown, about 3-5 minutes (keep an eye on them, they go from brown to black very fast). Remove with tongs or a slotted spoon to a plate lined with paper towels to drain. You may need to cook them in batches.
  • Distribute the shallots over the top of the casserole and serve immediately.

Notes

The mushroom gravy can be made up to 3 days in advance. Blend or whisk in a little more water or broth if it's too thick. The gravy can also be frozen for up to 3 months. Thaw overnight in the fridge.
The cooked casserole (without the shallot topping) can be refrigerated for up to 3 days. Toss everything again if necessary (the gravy might get watery but it'll blend again) and bake at 350 degrees for 30-40 minutes to reheat. Cook and add the shallot topping.
You can double the recipe, using a 9x13" baking dish, and bake for 30-35 minutes. However, triple the shallot topping (doubling won't be enough).

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