Keto Green Bean Casserole
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My keto green bean casserole recipe features tender green beans in a creamy homemade mushroom sauce, topped with crispy onions. It’s a family favorite! 3 grams net carbs.
When developing this low carb green bean casserole, there were two pain points: the cream of mushroom soup and the crispy fried onion topping.
The soup was the easy part: I simmered butter, heavy cream, and vegetable broth, which worked well as a stand-in for the soup. The onions, on the other hand, were quite a challenge.
I initially tried adding my keto onion rings on top, but my gosh, it was an insult to a green bean casserole. Instead, I coated the onions in milk, pressed almond flour into them, and, once fried, they did the whole dish justice.
These days, I don’t follow a keto diet, but my family has requested this very casserole for the past five years!
Table of Contents
Arman’s recipe highlights
- It’s fresh. I’m all for shortcuts, but I feel like what sets my casserole apart is skipping frozen green beans and canned soup.
- That addictive crunch topping. My secret is using milk or cream instead of an egg wash. That’s my favorite part of the whole casserole, which is why I had to perfect it.
- Easy to make ahead. When I visit home for the holidays, I’m always looking for ways to ease the crunch in my mom’s small kitchen. So I make this casserole ahead of time and pop it in the oven right before dinner. Assemble up to 2 days beforehand, then add the onions before baking.
Key Ingredients
Here’s what you’ll need, along with my kitchen notes. Full measurements are in the recipe card below.
- Fresh green beans. Some grocery stores trim them around the edges, but if not, just snip both ends.
- Oil. To fry the onions and mushrooms for the casserole base. I like using olive oil, but any neutral oil works fine.
- Onions. Softens and adds a subtle sweet flavor.
- Mushrooms. I like button mushrooms, but I’ve also had success with brown or Swiss mushrooms.
- Garlic. I prefer fresh garlic cloves for a more pronounced flavor, but jarred garlic works well in a pinch.
- Butter. I used unsalted butter. If you use salted butter, reduce the amount of added salt.
- Heavy cream. My secret ingredient! Many green bean casserole recipes call for milk or half and half, but I find heavy cream gives it a richer texture, like condensed cream of mushroom soup.
- Vegetable stock. Look for low-sodium stock so you don’t overpower the casserole. You can also use chicken broth or mushroom broth.
- Salt and black pepper. To taste.
For the fried onions:
- Onion slices. The thinner you slice the onions, the crispier the topping will be. I aim for about 1/8 inch.
- Milk OR heavy cream. To help the flour stick to the onions. I only recommend cream if you have some leftover from the casserole.
- Almond flour. To dredge the onions. I like using blanched almond flour or keto bread crumbs with crushed pork rinds. You can use almond meal, but the onions will be a little more rustic.
- Salt and black pepper. To taste.
- Oil. To shallow fry.
Can I use frozen green beans?
You can, but I don’t recommend it. Frozen green beans release a lot of water when baked, which thins the creamy sauce and makes the casserole soggy. If frozen is all you have, thaw them completely, pat them very dry with paper towels, and cut the baking time slightly so the sauce doesn’t turn watery.
How to make keto green bean casserole
Step 1- Prep work. Preheat the oven to 180C/350F and grease a casserole dish.
Step 2- Prepare the onions. In a small bowl, combine the onion topping ingredients and toss to coat.
Step 3- Fry the onions. Heat oil in a large skillet over medium heat. Once hot, add the onion mixture and fry for 4-5 minutes, until golden. Set aside.
Step 4- Cook the green beans. In a large pot, bring 3-4 cups of water to a boil. Once boiling, add the green beans and blanch for 3 minutes. Drain and transfer to a large bowl.
Step 5- Cook the mushrooms. Add olive oil to a large skillet over medium heat. Sauté the onions for 5 minutes, then add the garlic and mushrooms and sauté for 3-4 minutes. Transfer the veggies to the bowl with the green beans.
Step 6- Build the sauce. Return the skillet to the heat and add butter. Add the stock, cream, salt, and pepper, and simmer for 3-4 minutes. Pour the soup mixture over the green beans and stir to combine.
Step 7- Bake. Transfer the green bean mixture to the baking dish. Bake for 35 minutes, then sprinkle with the crispy onions. Return the dish to the oven and bake for 10 minutes or until bubbling.
Storage and make-ahead instructions
Make ahead: Prepare the casserole without the onions, then refrigerate for up to two days. Let it come to room temperature for 20 minutes before baking as directed. Fry the onions right before serving.
To store: Keep leftovers in an airtight container in the refrigerator for up to 3 days.
To freeze: Transfer the leftovers to a freezer-safe container and freeze for up to three months. The creamy sauce may separate, so stir well after thawing and before reheating.
Reheating: Microwave single servings in 30-second intervals or bake in a preheated oven until warm. Add onions at the end.
Keto Green Bean Casserole
Ingredients
For the onion topping
- 1 medium onion sliced
- 2 tablespoon milk of choice I used unsweetened almond milk
- 1/4 cup almond flour
- 1 teaspoon salt
- 1 teaspoon pepper
- 1 tablespoon olive oil
Instructions
- Preheat the oven to 180C/350F. Grease a medium sized baking dish and set aside.
- In a mixing bowl, make the crunchy onion topping. Add your onion, milk, almond flour, salt, pepper, and olive oil, and mix until all the onions are coated.
- Heat your oil in a non-stick pan on medium heat. When hot, add the onion mixture and stir fry for 4-5 minutes, until golden. Remove from the heat and set aside.
- In a deep pot or saucepan, heat up 3-4 cups of water until boiling hot. When hot, add the green beans and blanch them, by letting them simmer for 3 minutes. Drain and transfer into a large mixing bowl.
- In a non-stick pan, add the olive oil and place over medium heat. When hot, add the sliced onions and saute for 5 minutes. Add the garlic and mushrooms and saute for an extra 3-4 minutes. Transfer the vegetables to the bowl with the green beans.
- Place the pan back on the heat and add the butter. Once sizzling, add the vegetable stock, heavy cream, salt, and pepper, and let it simmer for 3-4 minutes, to thicken. Remove from the heat, pour over the green bean and vegetable mixture, and mix well.
- Transfer the green bean casserole to the greased baking dish. Bake for 35 minutes, before removing from the heat and topping with the crispy onions. Place back in the oven for a further 10 minutes, until the edges are bubbling.
Notes
Nutrition
More keto-friendly holiday recipes
Here’s how I recommend rounding out your holiday feast!
This is the first time I’ve enjoyed eating a green bean casserole. Delicious!
The sauce never thickened. Flavor was great, but more of a soup, not a casserole.
Sorry to hear this Jaimee. The easiest solution is to just make sure that you have simmered the sauce down until it reaches a thickness that you would like for your casserole, before baking. It can take several minutes for the heavy cream to properly thicken. Hope this helps!
What a hit this Easter!!! (We needed a low carb veg – 2 on a carnivore diet and 1 prediabetic.) They all told me to NEVER make the traditional g b casserole again – only this one. I did make some changes: added 8 slices of chopped sauteed bacon to beans (for 10 servings) – so yummy! Also put the topping mixture in oven for 10+ minutes before placing on top of beans – to make them crispier. I used frozen french cut beans. Next time I will reduce the liquids – maybe the frozen beans made the casserole too runny. A WINNER recipe!!
Is three cups of green beans enough for 8 servings?
Love your recipes!
Hi Janet, as smaller side portion that should be fine! If you’re not serving it with any other sides, I would increase the quantities so that everyone can have a bit more.
I’m now following your Instagram because of this recipe haha I love it!
I thought the same thing about the onions and then realized you cook the topping onions first and then in step 5 you are cooking the onions that are for the casserole along with the mushrooms and garlic. The crispy onions that you cooked first are then place on the top of the casserole and put back in the oven as indicated in step 7. I hope that helps.
Do you have a video of this recipe? If not, can you please do one? I’m failing miserably at the onions. They look SO GOOD in the photos and… I am inept at making keto crispy onions. 🙁
Don’t understand directions. Do you cook onions twice?
Hi J- The onions have been cooled since they have been prepped first, so they are re-heated once you add them to the casserole.