This classic green bean casserole recipe is made from scratch. Fresh green beans, creamy mushroom sauce and homemade crispy fried onions make every bite of this mouth-watering dish a welcome holiday side, without the carb load.
😍 Carbs in keto green bean casserole - 5g net carbs per cup
😋 Why you'll love this recipe
This yummy green bean casserole is naturally keto-friendly. One cup has only 5g of net carbs, because it is made with fresh, unprocessed ingredients.
Compare this to French’s green bean casserole, which has 20g of net carbs per cup. This is because traditional green bean casserole is made from canned condensed mushroom soup, canned green beans and canned crispy fried onions.
Carbs in green beans
A cup of green beans has only 4 grams of net carbs and 30% of the daily recommended value of vitamin C! Green beans are naturally low-carb and keto-friendly!
🥗 Diabetic diet
This recipe is diabetic-friendly, keto, low-carb, vegetarian, and nut-free so you can serve it to most of your family and friends. Skip the soy sauce to also make this a gluten-free green bean casserole.
Even if you aren't following a keto diet, the carbs in a Thanksgiving dinner can add up fast! Adding naturally keto dishes to your Thanksgiving feast helps to manage the total carb count for the entire meal.
Keto green bean casserole ingredients are fresh green beans, mushrooms, onion, garlic, thyme, butter, soy sauce, Worcestershire sauce, white wine, heavy cream, grated cheese, and oil to fry the onions.
Feel free to use broth or water instead of wine, the important thing is to cook the mushrooms in liquid to really bring out their flavor.
Fresh and frozen green beans are interchangeable. Frozen green beans are raw and must be cooked, either according to the package directions or blanched per the step by step instructions below.
You may substitute onions with leeks or shallots, these also taste lovely.
This green bean casserole uses cheese, rather than flour, to thicken the sauce, keeping it keto. Use any grated cheese that you like.
If you don't want to use cheese, you may add a ½ teaspoon of xanthan gum as a sauce thickener. This can be found in the gluten-free baking section at the supermarket.
You may substitute 2 cloves of fresh garlic with ¼ teaspoon of garlic powder.
🔪 Equipment you'll need
You need a large pot with a lid, a strainer, a large bowl for the ice bath, a knife, cutting board, a skillet, spatula or tongs and a 9x13 inch casserole dish.
👩🏻🍳 How to make green bean casserole with fresh green beans
Step 1: Trim green beans. Use fingers to snap off ends.
Step 2: Cut green beans into bite-sized pieces about 1-2 inches long.
Step 3: Blanch green beans in boiling water until bright green. Immediately transfer to an ice bath to stop the cooking process.
Step 4: Sauté mushrooms in butter with salt, pepper and thyme. Avoid greasy mushrooms by using the recommended amount of butter.
Step 5: Over high heat, deglaze the pan with wine. Let the wine cook down until reduced by half.
Step 6: Stir in heavy cream, soy sauce, Worcestershire sauce, grated cheese and garlic. Remove from heat.
Step 7: Fold in green beans.
Step 8: Transfer to a casserole dish. Bake in a 300°F oven for 20 minutes.
🧅 Crispy fried onions
Next, fry the onions while the casserole bakes. These are gluten-free french fried onions since they only contain 2 ingredients - onions and oil. Start with thinly sliced onions. I sliced my onion by hand. You can also use a mandoline slicer.
Fry onion slices in hot canola oil, the oil needs to reach a temperature of 350-375°F for golden-brown and crispy fried onions.
Be careful when working with hot oil. Use tongs. Be mindful to keep the tips of the tongs pointing down so that the hot oil does not run up the handle and burn your hand.
Step 1: Heat oil in a deep skillet or Dutch oven over medium-high heat. When the oil shimmers, test a slice by frying it.
Step 2: Working in batches, gently place onion slices in a single layer into the hot oil.
Step 3: When onions are golden-brown and crispy, transfer to a paper towel lined plate. Set aside.
Step 4: Finally, top the casserole with crispy onions and bake 5 more minutes before serving.
💭 Top tips
👆🏼 For crisp, bright green beans don't overcook them.
👆🏼 Avoid soggy green beans. Don’t leave blanched green beans soaking in an ice bath. Strain immediately.
👆🏼 Avoid greasy mushrooms. Instead of adding more fat while cooking mushrooms, add liquid to help them cook. Cook mushrooms as long as it takes to cook down the liquid, until you get golden-brown mushrooms.
👆🏼Fun fact: You can't overcook mushrooms, because they are fungi and fungi are made of chitin, rather than fiber. This makes them heat stable. They won't break down structurally with cooking the way meat, fruits and vegetables do.
You can't overcook mushrooms!Dan from America's Test Kitchen
👆🏼Do not drop onion into hot oil as this can cause the hot oil to splatter and burn someone.
👆🏼Don't overcrowd the pan when frying onions, or the onions will steam and get soggy rather than fry and crisp. Be patient, it only takes a few minutes. Use a whisk or spider to separate slices while they cook.
🛎 How to serve
Serve immediately or keep warm until ready to serve.
🐿 How to store
Store in an airtight container in the refrigerator for up to a week.
❄️ How to freeze
Store in an airtight container in the freezer for up to 6 months.
🧐 Frequently asked questions
Yes. Green beans have just 4g net carbs per cup. Out of all beans, green beans are the lowest in carbs.
Yes. Mushrooms only have 1.5g net carbs per cup.
Yes. Instead of butter, cook bacon to render the bacon fat. When crisp, set bacon aside and cook the mushrooms in the bacon fat. Prepare the casserole and top with bacon pieces before baking.
This keto green bean casserole is made from scratch with fresh green beans, creamy mushroom sauce and homemade fried onions. Enjoy!
- 1 pound fresh green beans
- 2 cups water and 2 cups ice for ice bath
- 2 tablespoons salted butter
- 12 ounces baby Bella or white mushrooms, sliced
- a pinch of salt
- a dash of black pepper
- 1-2 sprigs of thyme
- ⅓ cup dry white wine
- ½ cup heavy cream
- 1 teaspoon soy sauce (optional)
- 1 teaspoon Worcestershire sauce
- ¼ cup grated cheese (Parmesan or Gruyere are nice)
- 2 cloves garlic, minced
- ½ cup yellow onion, thinly sliced
- 1 cup canola oil
- Rinse and trim green beans, then cut them into bite-sized pieces about 1-2 inches long.
- In a large pot, bring a quart of water to a boil. While you wait for the water to boil, prepare an ice water bath of cold water and ice, in a large bowl. When the water comes to a boil blanch green beans for 2-3 minutes until they turn bright green. Use a strainer to transfer green beans to the ice bath for a minute or two to chill. This stops the cooking process, prevents them from overcooking, and helps them retain their bright green color and crispness. Drain green beans in a strainer. Do not leave them in the ice bath or they will become soggy. Set aside.
- In a skillet over medium-high heat, sauté mushrooms in butter with salt and pepper, and thyme. When the mushrooms absorb all of the butter, add white wine. Let the wine cook down until it reduces by half, about 5 minutes. Stir in heavy cream, soy sauce, Worcestershire sauce, grated cheese and garlic. Bring to a simmer, then remove from heat.
- Fold green beans into mushroom sauce and transfer the mixture to a casserole dish to warm in a 300°F oven for 20 minutes while you prepare the crispy fried onions.
- Heat oil in a deep skillet or Dutch oven over medium-high heat. I used a cast iron skillet. When the oil shimmers, test a slice by frying it. It should bubble up and cook to a crisp in a minute or two. Working in batches, gently place onion slices in a single layer into the hot oil. Do not drop them into the oil as this can cause the hot oil to splash and burn someone. Don’t overcrowd the pan or the onions will steam and get soggy rather than crisp. Be patient, it only takes a minute or two. Use a whisk or spider to separate slices while they cook. Fry onion slices in hot canola oil, the oil needs to reach 350-375°F. Fry for 2-3 minutes until golden brown and crispy. The onions will steam and the oil will bubble. You will know that the onions are just about finished cooking when the steaming and bubbling dies down. Transfer to a wire rack or paper towel-lined plate. Set aside.
- Before serving, top casserole with crispy onions and bake 5 more minutes.
- Make ahead a day or two before. Just transfer to a casserole dish, cover and refrigerate until ready to bake.
- For crisp, bright green beans don't overcook them.
- Avoid soggy green beans. Don’t leave blanched green beans soaking in an ice bath. Strain immediately.
- Avoid greasy mushrooms. Instead of adding more fat while cooking mushrooms, add liquid to help them cook.
- Cook mushrooms as long as it takes to cook down the liquid, until you get golden-brown mushrooms. You can't overcook mushrooms, because they are fungi and fungi are made of chitin, rather than fiber. This makes them heat stable. They won't break down structurally with cooking the way meat, fruits and vegetables do.
- Prep Time: 20 minutes
- Cook Time: 40 minutes
- Category: sides
- Method: bake
- Cuisine: American
Keywords: Keto green bean casserole, low-carb, nut-free, homemade, scratch, fresh green beans, Thanksgiving