Keto Green Bean Casserole
This Keto Green Bean Casserole Recipe is exactly what you need for your holiday meals. Creamy mushroom sauce and crunchy onion topping will remind you of the traditional green bean casserole with condensed soup and fried onion topping.
Classic green bean casserole is a tradition at Thanksgiving dinner, Christmas, Easter, potlucks, and other holiday meals in the US. I’ve been making it and eating it for as long as I can remember.
I had a reader email me her ideas for an easy low carb green bean casserole and I tried it and it was delicious. But it had cheese and bacon (two of my favorite ingredients, but not in traditional green bean casserole recipes). I’ve thought about sharing it a few times anyway but decided to wait on tradition and go for mushrooms and crunchy french fried onion topping instead in my keto version.
Last time I was in the grocery store I picked up a can of French’s Crispy Fried Onions and looked through the ingredients. They are pretty much just onions and flour. But how could I make the same flavor and texture without all the work involved with actually breading and frying onion slices?
Enter dried minced onions. They are crispy onions without all the added ingredients. And perfect for a delicious green bean casserole for your holiday meal that the whole family will love.
Ingredients
- Green beans – Fresh or frozen work fine. Using frozen simplifies the prep time.
- White mushrooms – I use fresh mushrooms. Either white button mushrooms or baby bella mushrooms also work well.
- Sour cream – I like the combo of sour cream and mayo for creamy sauces.
- Mayo – Any type of mayonnaise will work.
- Dried minced onion – This is my secret ingredient for an easy topping similar to french fried onions.
- Bouillon powder – I make my own based on nutritional yeast.
- Butter – I use salted butter in all of my recipes.
- Almond flour – For a nut-free dish, you can sub in sunflower seed flour.
- Salt & black pepper – Season to taste.
How to Make Keto Green Bean Casserole
Step One: Make the homemade condensed cream of mushroom soup sauce. Making the creamy sauce is as simple as stirring together the ingredients. No sauteing or cooking required.
Step Two: Thaw or steam your green beans.
Step Three: Mix together the sauce and the green beans in the casserole dish. This is when you can season the green bean mixture to taste with salt, pepper, or other spices of your choice.
Step Four: Stir together the topping ingredients and sprinkle on top of the casserole. Bake in the oven at 350 for about 25 minutes until it is hot and the topping is golden brown.
Leftovers: Store in an airtight container in the fridge for 3-4 days.
Top Tip💡
Since you are using dried minced onion, it saves the step of cooking onions that I’ve seen in many homemade green bean casserole recipes.
More Tips
I have a couple of tips for you when making this keto green bean casserole from scratch.
- Use frozen green beans – This saves time on having to steam fresh green beans.
- Chop frozen mushrooms – Mushrooms are not a vegetable that freezes well but they are much easier to finely chop (without making mushroom mush) when they are frozen. Simply pop your white button mushrooms in the freezer the day before making this. Then finely chop them in the food processor.
- Long beans – If your green beans are very long cut them into bite-sized pieces. If they are very thick you can cut them in half lengthwise.
- Make-ahead – This is a great make-ahead side dish! To make this ahead of time bake the green beans in the sauce without the topping. Cool and refrigerate. When you ready to serve just add the topping and bake again until the green beans are hot.
Variations
- Crushed Pork Rinds – If you want to bulk up the crunchy topping you can mix in some crushed pork rinds (aka pork panko) before putting it on the casserole. These are the best way to make a breading for the keto diet.
- Cheese – If you normally add cheese to this dish go ahead and add some! Parmesan cheese, mozzarella cheese, or cheddar cheese all work well with the other flavors.
- Bacon – Is bacon ever not wanted? Mix in some cooked crumbled bacon to the sauce for a pop of flavor.
Common Questions
Where did green bean casserole originate?
Did you know that Campbell’s Soup is actually the inventor of the green bean casserole?
The green bean casserole was first created in 1955 by the Campbell Soup Company. Dorcas Reilly led the team that created the recipe while working as a staff member in the home economics department. – Wikipedia
That is one way to boost sales of condensed canned soup! Sorry, Campbells, I cut you out entirely of this recipe. But will give credit for the creation of this delicious holiday side dish. We really love it any time of the year.
Should I Use Fresh or Frozen Green Beans?
Either will work for this keto recipe but it is easier to use frozen. If you use fresh green beans you need to boil or steam and drain them first.
In a pinch, you can use canned green beans but they are at the bottom of my list. Fresh or frozen cooked green beans taste much better.
Can I Make This Ahead?
Yup! This low carb keto green bean casserole can be made up to 2 days ahead. Just prep it in the baking dish of your choice covered with a lid or plastic wrap and pop into the fridge but keep the topping separate and add that right before baking for your Thanksgiving table. Two of my other keto recipes for the holiday season are this Keto Mashed Cauliflower with Cream Cheese and Keto Creamed Spinach.
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Keto Green Bean Casserole
Ingredients
- 1 lb frozen green beans, thawed (if using fresh steam them first)
- 1 cup white mushrooms, very finely chopped (about 5 large mushrooms)
- 1 cup sour cream
- 1/2 cup mayo
- 2 tbsp dried minced onion
- 1 tsp bouillon powder (or bouillon paste)
- 1 tsp salt
- 1/2 tsp pepper
Topping:
- 1/4 cup dried minced onion
- 2 tbsp butter, melted
- 2 tbsp almond flour (or sunflower seed flour)
Instructions
- Preheat oven to 350.
- Mix together the finely chopped mushrooms, sour cream, mayo, and spices. Fold in the green beans. Spread in an 8 x 8 baking dish.
- Mix the topping ingredients. Sprinkle over the green beans.
- Bake for 25-30 minutes until hot, bubbly, and the topping is golden brown.
Notes
Nutrition
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Originally Published November 9, 2018. Revised and Republished September 23, 2025.
This is one of my favorite recipes for green bean casserole. So easy to make too!
This was a great replacement for our high-carb green bean casserole. Everyone loved in my family asked for seconds.
Made this with no changes to the recipe. One of my new favorites. Even my family not on keto thought this was absolutely delicious.
Thank you for the recipe!
Is the nutritional info at the bottom of the recipe for the entire recipe or for 1 serving?
1 serving
My wife is pregnant and had the sudden craving for green bean casserole. Myself, being keto wanted to eat this as well so I decided to make this for the both of us. IT WAS SO GOOD!
My deviations: I used caned mushrooms (1.5 of the little cans) , and caned french green beans (2 standard cans), chicken bouillon cubes (2 of them diced down to powder and mix with a little water prior to mixing). After 30mins in the oven I added a thin layer of cheddar cheese and broiled for 5mins.
I Will make this again! Thanks!
This is Great! We had it for Thanksgiving Dinner! Highly recommend!
If using canned beans how many cans would I need?
I think 2 cans would be good.
<Members of my family are alergic to Mushrooms, can you substitute chicken soup instead?
Do you mean a can of soup? It would be better to just leave out the mushrooms.
How would I convert the serving size into ounces?im new to keto and use an app to help me stay at my 30 carbs a day.I can enter my own recipes but it require servings in ounces to calculate the carbs,protien and such.
The easiest thing to do is weigh your baking dish empty and then after the casserole is baked. Divide by the serving number.
This recipe is soooo delicious! Sometimes when I try a new recipe and ask my husband what he thinks, he says ‘it’s pretty good.’ With this one, he went on and on about it! I’ve made it twice this week, because we like it so much! I honestly think it’s better than the traditional recipe, and I always loved that. Also, it’s super easy, which is definitely a plus!
Note- for the bouillon I used Better then Bouillon paste, veggie flavor. We’re also eating Keto right now, and this is perfect!
What kind of bouillon did you use? It doesnt say if chicken or beef?
I used chicken.
Can you make this ahead of time as a freezer dish?
I’m not sure if that would work. Especially if you are using frozen green beans to start. If you try please let us know how it turns out.
I am allergic to soy and do not use mayo. What would be a good substitute for the mayo??
There are soy free mayos out there. But if you prefer to not use mayo at all softened cream cheese should work.
Thanks so much! Can’t wait to try it!
This is a favorite but needed a healthier version this year, this looks perfect!
This recipe will definitely be on our Thanksgiving table! Thank you so much for sharing!
Would it work with nonfat Greek yogurt instead of sour cream?
Yes, that should be fine.