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Low Carb Green Bean Casserole -by amber's hands-

Back when I wrote up my favorite keto thanksgiving recipes, I told you I had been working on a low carb green bean casserole recipe but that I didn’t have it quite to where I wanted it. And I promised you I’d have it ready before Christmas. So here it is!

It’s not that there aren’t other low carb green bean casseroles out there. There are. But I couldn’t find a single one that had fried onions. And I really, really like fried onions in my green bean casserole. So while it’s a little more work to fry your own onions (the kind in the can aren’t low-carb) it’s absolutely worth it to me. I wanted this to have all the familiar flavors of the traditional green bean casserole, but with the exquisite flavors that only come from using fresh ingredients instead of canned. I used fresh green beans but I think you could also substitute frozen and get a similar result.

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The Beans

Low Carb Green Bean Casserole -by amber's hands-

I used the haricot vert beans from Trader Joe’s, which I cut into thirds. They’re a thin, fresh green bean, and I just like them a bit better. But you can use regular green beans as well. Side note: I seriously can’t help but want to type “green beens.” It’s physically difficult to stop myself.

After experimenting a bit, I found it works better to boil the beans in salted water until they’re your desired doneness. They will cook a little bit in the oven, but not enough to get them to the right tenderness if you undercook them. I liked my beans after about ten minutes in the boiling water, but if you like yours crisper you may like them at seven. Or if you use larger beans, they may need more time. Using frozen will also impact the amount of time. Basically what I’m saying is that you need to check them and take them out whenever they’re delicious to you. Once they’re done, put them into ice water to stop them from cooking. You can do this a day ahead, then drain and store in the refrigerator.

The Onions

For this recipe, I chose shallots over onions. I did this because I think shallots are a closer flavor to the fried onions you get out of the can and generally a more interesting flavor than onions. Also they’re a nicer size.

Low Carb Green Bean Casserole -by amber's hands-

Here’s what you want to do. Get either one enormous shallot or two average-sized ones. Slice them into 1/4 inch rounds, and then separate the larger outer rings from the smaller ones. Leave the larger rings as they are and chop the small ones. Set the chopped ones aside.

Low Carb Green Bean Casserole -by amber's hands-

To fry them, I first tossed them in oat fiber. Oat fiber is an unusual ingredient you may not have in your pantry, so I think you could skip it altogether if you prefer. I just think it helps the batter to adhere a little better. You could also use arrowroot powder in this, as it may be easier to come by. It has more carbs, but it’s a very small amount that will be sticking to the shallots. 

I used egg white as the binder, but when it came to what to dip them in last, I had to do several trials to find something that worked. My initial thought was that almond flour would be the best option, but I found it to be sort of crumbly when fried. Not the texture I was going for. Then I found a recipe on I Breathe I’m Hungry that used equal parts coconut flour and parmesan cheese. I was hesitant to use coconut flour because, while I like coconut, I find it out of place in most savory applications. However, when it’s mixed with parmesan cheese and fried up on an onion, I don’t notice any coconut flavor at all.

As far as oils go, avocado is your best bet for the higher temps of frying, but if you can’t use that, you can also use ghee or clarified butter.

Low Carb Green Bean Casserole -by amber's hands-

Once they’re fried, place them momentarily on a paper towel, then transfer to a rack to cool completely.

The Sauce

The typical sauce for a green bean casserole is a can of cream of mushroom soup. But that has wheat and food starch and extra carbs we don’t need. So I had to make a substitute.

Low Carb Green Bean Casserole -by amber's hands-

I took the chopped shallots and sautéed them with diced mushrooms. I added some thyme and a little sherry for extra flavor but those are optional, and if you want it to taste the most like the canned stuff, leave those out. Then I separated the mushroom mixture into two parts.

Low Carb Green Bean Casserole -by amber's hands-

The first half I added to a mixture of chicken broth and cream, with a dash of Worcestershire sauce. Worcestershire sauce does contain a small amount of sugar, so if you’re not comfortable with a trace of sugar (seriously, it’s so small per serving) you could use Tamari or coconut aminos. Just something to help up the savory flavor a little. Then I used my immersion blender to blend it into a sauce.

I added a little xanthan gum to thicken it a little more, but if you don’t mind your sauce a little thinner you can skip it. The mushrooms do add some thickness already.

Assembling the Casserole

Low Carb Green Bean Casserole -by amber's hands-

Add the sauce and the other mushrooms to the drained green beans, and pour into a casserole dish. I used a 1.5 quart dish.

Low Carb Green Bean Casserole -by amber's hands-

Cover with foil and bake 15 minutes, then take the foil off and add the fried onions and bake for another 5.

Low Carb Green Bean Casserole -by amber's hands-

There you have it! Low carb green bean casserole.

Make Ahead Tips:

I know the holidays are busy times, so I tried a few things to see what works best for making some of this ahead.

  • You can easily cook the beans a day ahead, and also chop the mushrooms. This led to the best results for me.
  • You can also assemble the casserole except for the fried shallots and refrigerate, covered, overnight. However, this will increase the time it needs to bake by about double to get it heated through all the way. If you double the recipe, it will take even longer.
  • The fried shallots will get soggy if made ahead. They will crisp up a bit in the oven, but they are really much better if they’re fried the same day.
Low Carb Green Bean Casserole -by amber's hands-

What’s your favorite holiday side?

Low Carb Green Bean Casserole

  • Servings: 6
  • Difficulty: Intermediate
  • Print

Low Carb Green Bean Casserole -by amber's hands-Ingredients:

1 lb | .45 kilo fresh green beans (can sub frozen)
10 oz. | 280g mushrooms (I like crimini/baby bellas)
1 large or 2 average shallots
1 Tbsp oat fiber (optional, could also use arrowroot powder)
1 egg white
1 Tbsp coconut flour
1 Tbsp finely grated parmesan cheese
avocado oil or ghee for frying
1 tsp thyme (optional)
2 Tbsp | 30 mL Sherry or white wine (optional)
2 dashes Worcestershire sauce (optional, may sub tamari or coconut aminos)
1/2 cup | 120 mL chicken broth
1/2 cup | 120 mL heavy whipping cream
1/4 tsp xanthan gum (optional)
salt & pepper


1.Bring a large pot of salted water to boil. Boil beans until they reach desired doneness, 7-10 minutes. Drain and place immediately in a bowl of ice water to stop cooking. Once cool, drain and set aside, or cover and refrigerate for up to one day.
2.Prepare shallots: slice shallots into 1/4 inch rounds and separate large outer rings from inner rings. Chop inner rings finely and set aside. Place larger rounds in a bowl and toss with oat fiber to coat lightly. In another bowl, whisk egg white until foamy. In a third bowl, mix coconut flour with parmesan cheese and a pinch of salt.
3.Heat enough oil or ghee to coat the bottom of a heavy skillet over medium heat until hot. Place shallot rounds (no more than a few at a time) in egg white. Coat, then let excess drip off. Dredge in the coconut flour mixture to lightly coat, then fry in oil. Turn as they brown on one side, then brown on the other. These will brown quickly, so watch carefully. Repeat until all shallots are fried. Transfer briefly to paper towels, then cool completely on a wire rack.
4. Dice mushrooms. Heat 1 Tbsp oil or ghee in another skillet. Add mushrooms and chopped shallots. Add salt, pepper and thyme. Sauté, stirring constantly, until mushrooms are nicely browned. If using, deglaze the pan with sherry and cook until liquid is evaporated. Divide the mushroom mixture into two. Add one half to the beans.
5. Heat chicken broth & cream in a small to medium saucepan until it begins simmering. Add the other half of the mushrooms, and blend with an immersion blender until smooth (alternatively, place all ingredients in a blender.) If using, add xanthan gum and heat, whisking constantly, until thickened. Season with salt & pepper to taste.
6. Add sauce to green bean mixture. Mix gently. Add more salt & pepper if needed. Place mixture in a casserole dish and cover with foil. Bake at 375° for 15 minutes. Uncover and add fried shallots to the top and bake another 5 minutes.

This recipe is easily doubled.

Makes 6 servings. Per serving:  Calories: 267 kcal; Carbs: 10.7g; Fiber 2.8g; Net Carbs: 7.9; Fat: 22.9g; Protein 4.8g


Low Carb Green Bean Casserole -by amber's hands-

1 Comment on Low Carb Green Bean Casserole

  1. I make mine very similar to yours, but add some cream cheese and mature cheddar cheese .and make it every year for our British friends and they absolutely love it! (I confess that I am too lazy to fry up the onions and will just use the store bought crispy onions as I figure the carb total is low enough for what i am eating)

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