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.
Sounds delicious, but is there a substitute for mayo? Sadly, I can’t have that.
Additional sour cream or Greek yogurt.
Curious if I can use coconut flour instead of almond? I would like to make this for Christmas but my mother-in-law is allergic to almonds
A better swap would be crushed pork rinds if you have them. Otherwise try using 1 tablespoon of coconut flour but I’m not positive that would work.
I know I’m late to the conversation, but I too have an almond-allergic in-law, and have found that the 1-1 substitute for almond flour is sunflower seed meal. It’s expensive in the meal form, but unroasted sunflower seeds are usually reasonably priced and easy to process with either a food processor, Vitamix or repurposed coffee grinder. I haven’t tried it myself yet, but have a plethora of recipes saved to attempt for my sweet sis-in-law, who’s finally decided low carb is the way forward.
For some reason mine is a little watery. The flavor is great but more watery than creamy. What did I do wrong or what can I do to prevent the watery liquid around the edges and bottom of dish after I scoop some out.
Thank you
Did you fully thaw the green beans? That is important. If they were even partially frozen they will release more liquid as it cooks.
You can mix in a bit of xanthan gum or glucomannan to help the sauce thicken. Try 1/2 teaspoon.
This recipe is amazing! Thank you so much. I eat GF and this is the easiest and tastiest version I have found. xoxo, and again, thank you so much for this recipe!!
This was amazing. It tastes just like the unhealthy version. The longest thing to make was the bullion mix. I also used 0% Fage Greek Yogurt instead of the sour cream because it is what I had in stock.
This looks so good! Was just curious if anyone has ever tried this recipe with crushed pork rinds on the top?
This was amazing and definitely a make again meal