Keto Green Bean Casserole
Published November 1, 2023 • Updated February 27, 2026
This post may contain affiliate links. See my disclosure policy.
I make this green bean casserole with fresh ingredients and a homemade mushroom cream sauce (no canned soup). The crispy fried onions are made with pork rinds, and the whole thing comes together in about 45 minutes.
This casserole only shows up once a year at my house, which makes it special. Sure, rolls and stuffing get made year-round, but this one’s reserved for Thanksgiving.
I switched to making this from scratch about five years ago after one too many gray-green, mushy casseroles from the canned stuff. The canned cream of mushroom soup was the biggest problem. It made everything taste like salt and starch, and the texture was paste. Now I make my own mushroom cream with real butter, fresh mushrooms, garlic, and a pinch of nutmeg (that nutmeg adds a warm, nutty undertone most people can’t place but always notice). The whole sauce comes together in about 10 minutes, and the flavor difference is night and day.
Traditional versions pack over 50g carbs per serving, mostly from flour-thickened soup and breadcrumb topping. This low carb version comes in around 4g net carbs. I use arrowroot powder instead of flour (it has 7x the thickening power, so I only need 1 1/2 teaspoons for the whole batch) and crushed pork rinds instead of French’s Fried Onions. The whole thing is naturally gluten-free too, no modifications needed.
What makes this recipe different?
- Fresh beans, not canned. I blanch them in salted water for 1-3 minutes, then straight into an ice bath. They come out bright green and crisp-tender instead of that dull olive mush you get from a can.
- No cheese. Cheese doesn’t belong in this dish. The classic version uses cream or half and half for a silky mushroom sauce. Other keto versions add mozzarella or cream cheese as a thickener, which changes the whole flavor profile.
- Arrowroot instead of flour or xanthan. I use arrowroot powder because it thickens cleanly at a fraction of the amount. I’ve tested xanthan gum here and it makes the sauce slimy.
- Pork rind onion topping that stays crunchy. I toss thinly sliced onions with baking powder and crushed pork rinds, then bake them at 425 until golden. They hold up under the final bake, which is more than I can say for most breadcrumb toppings.
How to make keto green bean casserole
I break this down into four parts: crispy onion topping, blanched beans, homemade mushroom cream, and final assembly. The onions take the longest, but they can be made ahead.
- Crispy onion topping. I toss thinly sliced onions with baking powder (or cornstarch or protein powder), pork panko (ground pork rinds), and seasoning, then bake them until they’re golden and crispy.
- Blanched beans. Fresh beans get blanched in boiling water for 1-3 minutes, then straight into an ice bath. This keeps them bright and crisp-tender instead of overcooked and gray.
- Homemade mushroom cream. I saute white mushrooms in butter with garlic and a pinch of nutmeg (adds a warm, nutty undertone). Then I thicken chicken broth and heavy cream with arrowroot powder to make the sauce.
- Assemble and bake. The beans get mixed into the mushroom sauce, topped with fried onions, and baked until bubbly.
Explore 684+ keto recipe videos with step-by-step instructions, tips, and tricks to make keto easy.
Keto Fried Onions Ingredients
1/2 medium onion, thinly sliced -
1 teaspoon baking powder or 1 tablespoon cornstarch
-
1/4 cup pork panko
-
1/2 teaspoon salt
-
nonstick cooking spray
Keto Green Bean Casserole Ingredients
-
1 lb fresh green beans, ends trimmed & halved
-
2 tablespoons unsalted butter
-
10 oz white button mushrooms, quartered
-
1 teaspoon salt, divided
-
1/4 teaspoon black pepper
-
2 cloves garlic, minced
-
1/4 teaspoon ground nutmeg
-
1 1/2 teaspoon arrowroot powder
-
1 cup chicken or vegetable broth
-
3/4 cup heavy whipping cream
Step by Step Instructions
Step by Step Instructions
Coat onions
Preheat oven to 425°F. Toss onions, baking powder (or cornstarch), pork panko and salt together in a large mixing bowl. Spread on a parchment lined baking sheet. Spray with cooking spray.
- 1/2 medium onion, thinly sliced
- 1 teaspoon baking powder or 1 tablespoon cornstarch
- 1/4 cup pork panko
- 1/2 teaspoon salt
Fry 'em til they're crispy
Bake the onion rings at 425°F for 18-25 minutes, tossing every 6-7 minutes, until crispy and golden brown.
Blanch green beans
Fill a large saucepan with enough water to cover the green beans (but don’t add them yet). Add a few sprinkles of salt. Bring to a boil. Once boiling, add green beans and let them boil for 1-3 minutes. Taste one to check if it’s cooked through. Drain and immediately transfer the beans to an ice bath. Once cooled, drain again and set aside.
- 1 lb green beans, trimmed and halved
Sauté mushrooms
Melt butter in a large skillet over medium heat. Add mushrooms, 1/2 teaspoon salt, and pepper. Cook 5 minutes until the mushrooms start releasing their liquid. Stir in minced garlic and nutmeg. Cook 1-2 more minutes until fragrant.
- 2 tablespoons butter (unsalted)
- 10 oz mushrooms, quartered
- 1/2 teaspoon salt
- 1/4 teaspoon pepper
- 2 cloves garlic, minced
- 1/4 teaspoon ground nutmeg
Make cream of mushroom soup
Sprinkle arrowroot powder over the mushrooms and stir to coat. Pour in the broth while stirring and simmer for 1 minute. Add heavy cream and cook for 6-8 minutes, stirring occasionally, until the sauce thickens.
- 1 1/2 teaspoons arrowroot powder
- 1 cup chicken or vegetable broth
- 3/4 cup heavy cream
Add green beans
Add blanched green beans to the cream of mushroom soup and stir to combine. Stir in remaining 1/2 teaspoon salt.
Make it a casserole
Transfer the green bean mushroom mixture to a baking dish or casserole dish. Top with fried onions. Bake at 400°F for 15 minutes or until hot and bubbly.
Nutrition disclaimer
The nutrition information provided is an estimate and is for informational purposes only. I am a Doctor of Pharmacy (Pharm.D.); however, this content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always consult your physician or other qualified health provider before making any lifestyle changes or beginning a new nutrition program.
Your Macros. Your Recipes. Calculated in 60 Seconds.
Get personalized keto macros and instantly see which recipes fit your targets. No more guessing what to eat.
Get My Macros + Recipes →Frequently Asked Questions
Can I use frozen green beans instead of fresh?
I always reach for fresh because the texture holds up better, but frozen works when that's what you have. I cook them according to the package directions first, then drain them really well before mixing into the sauce. The biggest difference is frozen beans release more water during baking, so I sometimes add an extra half teaspoon of arrowroot powder to keep the sauce from thinning out.
What is pork panko and is there a substitute for it?
Pork panko is ground up pork rinds. You can buy them already crushed or make your own by blending pork skins in a food processor until they turn into fine crumbs. If you can't use pork rinds, I've tried grated parmesan cheese and it gives decent crunch. I will say this: baking powder alone won't get the onions crispy. The pork panko is doing the structural work, so you need some kind of coating that crisps up.
Can this casserole be made dairy-free?
Yes, I've done it. I use almond milk, hemp milk, or macadamia nut milk instead of cream. Since nut milks are thinner, I add a bit more arrowroot powder to thicken the sauce. I swap the butter for coconut oil or avocado oil. The flavor is a little different (you lose that buttery richness) but the texture holds.
How do I keep the fried onions crispy?
I cut all the onions to the same thickness so they cook evenly. A mandoline helps here. If I make them ahead of time, I reheat them in the air fryer or oven for a few minutes right before topping the casserole. If your onions are already dark brown, don't add them before the final bake or they'll burn. I just sprinkle them on top right after it comes out of the oven.
How do I fix a watery casserole?
I put the baked casserole back in a skillet and cook it over medium heat until it thickens. If it's really loose, I whisk a bit more arrowroot powder into a tablespoon of cold broth and stir that in. It tightens up in a couple minutes.
Is this gluten-free?
Yes. I use arrowroot powder instead of flour for the thickener and pork rinds instead of breadcrumbs for the topping. There's nothing in my version that contains gluten. If you're buying pork panko pre-made, just check the label to make sure nothing was added during processing.
Do I need canned cream of mushroom soup?
No, and I'd skip it even if you're not keto. I make the mushroom sauce from scratch with butter, fresh mushrooms, garlic, chicken broth, and heavy cream. It takes about 10 minutes and tastes completely different from the canned version. I switched away from canned years ago after one too many batches that tasted like salt and paste, and I haven't looked back.
My mom has pushed green beans around her plate her whole life. Wasn't optimistic when I made this for Sunday dinner. She went back for more and asked what I put on the onions. When I told her pork rinds, she looked at me like I'd lost my mind, then immediately had another scoop.
My husband is a green bean casserole traditionalist (his mom always made it with the Campbell's soup), so I was genuinely nervous to put this in front of him. He took one bite of the onion topping and asked if I bought those crispy onions somewhere. When I told him it was pork rinds baked in the oven, he went quiet for a second and just kept eating. Sold.
That quiet second before he kept eating is better than any compliment. Pork panko wins over the Campbell's loyalists more than you'd think.
Threw in some shredded gruyere on a whim and now I can't go back. The pork rind topping still crisped up fine despite the extra moisture, so worth trying.
Gruyere with mushrooms, why did I not think of that. The pork panko holds up so much better under moisture than breadcrumbs would.
Make the pork rind onions the night before if you have time. They stay crispy in an airtight container and you cut at least 25 minutes off dinner prep the next day. The sauce comes together so fast that you barely miss the head start.
Made this three times now and I keep coming back to it on cold nights like these. The pork rind onion topping is SO good, and I've ditched the arrowroot powder in favor of a little cornstarch the last couple times since that's what I have on hand. My husband actually asked for it again last week, which never happens with casserole.
Cornstarch works great there (it's actually in the recipe as the swap option). And a husband who asks for casserole again -- that's rare.
Making this for Sunday dinner but my husband won't touch pork rinds -- if I skip the pork panko on the onions and just use baking powder, will they still crisp up, or do I need a substitute?
Baking powder alone won't get them crispy -- the pork panko is doing the real work there. If he's avoiding pork rinds, crushed almond flour crackers or finely crushed pecans are your best bet. They won't crisp up as much, but you'll still get some texture.