Keto Green Bean Casserole

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 at 5g net carbs per serving. 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. If you buy pork panko pre-made, check the label to make sure nothing was added during processing.

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.

Are green beans keto?

Yes. A cup of raw beans has about 4g net carbs, which fits comfortably into most keto macros. I eat them regularly, not just at Thanksgiving. Sauteed with bacon is my weeknight go-to, and brussels sprouts with bacon is the other side I rotate in.

The bigger carb question is what goes around the beans. A traditional casserole adds flour-thickened soup, breadcrumb topping, and sometimes sugar in the onion coating. That pushes a single serving past 50g carbs. I kept this version to 5g net carbs per serving by swapping the thickener to arrowroot and the onion coating to crushed pork rinds. No texture lost.

If you’re building a keto Thanksgiving plate, this fits right next to sweet potato casserole, turkey, and whatever else you’re serving without anyone doing carb math at the table.

Substitutions

For the beans

I always use fresh, but frozen or canned work if that’s what you have. For frozen, cook them according to the package directions first, then drain well. 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. For canned, drain and pat dry before mixing into the mushroom cream (canned releases a lot of extra liquid otherwise).

I’ve also made this with broccoli florets, chopped cauliflower, sliced brussels sprouts, chopped kale, and diced zucchini. All work. If you want a completely different casserole base, try loaded cauliflower casserole or cauliflower gratin.

For the cream of mushroom

If you don’t want to make the mushroom sauce from scratch, there’s a low carb version from Kettle and Fire that works in a pinch.

Instead of white button mushrooms, I’ve used cremini and portobello (portobello gives a deeper, meatier flavor). Beef or vegetable broth can replace the chicken broth. Half and half or nut milk can replace the heavy cream, just add a little more arrowroot if you go the nut milk route since it’s thinner.

For the crispy onions

You could use French’s Fried Onions if you really wanted to. They’re fairly low carb at 3g per 2 tablespoons.

Instead of crushed pork rinds, I’ve tried grated parmesan cheese and just more baking powder. Parmesan gives decent crunch. To replace the onions entirely, top the casserole with chopped walnuts, pecans, or parmesan crisps.

Make ahead and storage

I prep as much as I can the day before Thanksgiving so I’m not scrambling on the actual day. My cornbread stuffing gets the same treatment, and having both ready the night before makes Thanksgiving morning manageable.

Planning ahead

• Clean and trim beans 1 day ahead. I store rinsed and dried beans in a ziplock bag in the fridge.
• Slice onions and prepare coating 1 day ahead. I store coated onions in an airtight container at room temperature. They’ll re-crisp during the final bake.
• Make mushroom sauce 2 days ahead. I let it cool completely before storing in an airtight container in the fridge.
• Assemble the casserole up to 1 day in advance. Don’t add the fried onions yet or they’ll get soggy. Cover and refrigerate.

Storage

• I store leftovers in an airtight container in the refrigerator for up to 5 days.
• I freeze this for 1-3 months if wrapped tightly. I don’t freeze it with the fried onions on top (they go soggy). Make fresh onions the day you serve it. To cook from frozen, bake at 400 degrees F for 30-45 minutes until heated through and bubbly.

Reheating

• Oven. I preheat to 350 degrees F, transfer to an oven-safe dish, cover with foil, and bake 20-25 minutes.
• Microwave. I portion leftovers into microwave-safe dishes and heat on High in 30-second intervals, about 1-2 minutes total. Let stand 2 minutes before serving.
• Stovetop. I transfer to a saucepan over medium heat, add a couple tablespoons of water or broth to prevent sticking, and heat through for 5-10 minutes, stirring occasionally.
• Air fryer. I portion into air fryer-safe dishes and air fry at 360 degrees F for 4-6 minutes.